Antibodies specific to glycosylated pd-l1 and methods of use thereof

ABSTRACT

Antibodies that bind specifically to glycosylated PD-L1 relative to unglycosylated PD-L1 are provided. Antibodies that recognize specific epitopes of glycosylated PD-L1 protein and can block the binding of PD-L1 to PD-1 are provided. In some aspects, PD-L1 polypeptides comprising glycosylated amino acid residues at amino and carboxy terminal positions of the PD-L1 extracellular domain are also provided. Methods for making and using such antibodies and polypeptides (e.g., for the treatment of cancer) are also provided.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has beensubmitted electronically in ASCII format and is hereby incorporated byreference in its entirety. The ASCII copy, created on Mar. 25, 2016, isnamed 24258.105003PCT_SL.txt and is 41,706 bytes in size.

RELATED FIELDS

The present disclosure relates generally to the fields of molecularbiology, medicine and oncology. More particularly, new antibodies thatspecifically bind glycosylated PD-L1 and their use for treating cancersare provided.

BACKGROUND

Perpetuation of T-cell activation has drastically reshaped the treatmentof a broad spectrum of malignant cancer. For instance, the developmentof ipilimumab, the first FDA approved checkpoint blockade targetingT-cell response made treating metastatic melanoma probable (Hodi, F. S.et al., 2010, NEJM, 363:711-723; Robert, C. et al., 2013, Clin. CancerRes., 19:2232-2239; and Robert, C. et al., 2011, NEJM, 364:2517-2526).While the anti-cytotoxic T lymphocyte antigen-4 (CTLA-4) monoclonalantibody showed promising results in treating melanoma patients,second-generation checkpoint inhibitors targeting either PD-1 or PD-L1have demonstrated better clinical activity and safety in phase IIIclinical trials (Topalian, S. L. et al., 2012, NEJM, 366:2443-54; andBrahmer, J. R. et al., 2012, NEJM, 366:2455-2465). Because PD-L1 alsopossesses oncogenic potential that induces cancer cells progression(Topalian, S. L. et al., Id.; Page, D. B. et al., 2014, Ann. Rev. Med.,65:185-202), in addition to its immunosuppression activity, targetingthe PD-1/PD-L1 interaction provides dual efficacy by blockingimmunosuppression via PD-1 while reducing cell progression via PD-L1 andis expected to have more sensitive outcome (Topalian, S. L. et al., Id.;Brahmer, J. R. et al., Id.; and Hamid, O., 2013, NEJM, 369:134-144). TheUS FDA has approved two anti-PD-1 therapeutic antibodies for treatmentof certain cancers: KEYTRUDA® (pembrolizumab) and OPDIVO® (nivolumab).While there have been several successful clinic trials with promisingoutcomes (Page, D. B. et al., Id.), the pathophysiological function andregulatory mechanism of PD-L1 remains incompletely defined.

Reawakening silenced immune response, particularly effector T-cells, hasbeen recently added to a repertoire of treatment options after surgicalremoval, chemotherapy, radiotherapy, and targeted therapies. While theuse of anti-CTLA-4 monoclonal antibody (Dunn et al., 2002, Natureimmunology, 3:991-998; and Leach et al., 1996, Science, 271:1734-36)initially demonstrated success in treating metastatic melanoma, it hasbeen shown to also induce an autoimmune response. Unlike anti-CTLA-4antibodies, which affect only immune cells, anti-PD-L1 antibodies andanti-PD-1 antibodies act at a cellular level and at tumor sites to blockthe interaction between PD-1-expressing effector T-cells andPD-L1-expressing tumor cells. This creates a dual impact from both thetumor cell and the T-cell, thereby limiting the adverse effects andproviding better therapeutic efficacy (Okazaki, T. et al., 2013, Natureimmunology, 14:1212-1218). There remains a need for new and moreeffective therapeutics and methodologies that successfully target thePD-1/PD-L1 pathway and activate effector cells of the immune system toattack the tumor cells and treat cancers.

SUMMARY

The inventors have discovered that glycosylation of PD-L1 (also known asCD274, PDCD1L1, or B7-H1) expressed on tumor cells promotes or enhancesbinding to PD-1 expressed on immune effector cells, such as T cells,thereby increasing the suppression of T cell activity against the tumorcells. The inventors have identified antibodies that specifically andpreferentially bind to glycosylated human PD-L1 polypeptide relative tounglycosylated human PD-L1 polypeptide and block or inhibit binding ofglycosylated PD-L1 to PD-1. As used herein, such antibodies specific forglycosylated human PD-L1 and that inhibit binding of glycosylated PD-L1to PD-1 are referred to as “anti-glycPD-L1 antibodies.”

Further provided are methods of treating cancer, particularly cancerswhose cells express or overexpress PD-L1, in a subject in need thereofby administering one or more of these anti-glycPD-L1 antibodies. Theanti-glycPD-L1 antibodies as described herein inhibit or block theinteraction between PD-1 and PD-L1, which, in turn, inhibitsimmunosuppression that results from the PD-1/PD-L1 interaction, thusallowing the perpetuation of the cytotoxic activity of PD-1-expressingeffector T-cells against tumor cells that express PD-L1, animmunosuppressive ligand expressed by tumor cells. By inhibiting thePD-1/PD-L1 interaction, the anti-glycPD-L1 antibodies as describedherein can enhance effector T-cell responses and mediate anti-tumoractivity. As used herein, the terms unglycosylated PD-L1 andnon-glycosylated PD-L1 are used interchangeably. Unless otherwiseindicated, “PD-L1” as used herein refers to PD-L1 protein, polypeptide,or peptide, particularly human PD-L1 (the amino acid sequence, includingthe signal sequence, of which is SEQ ID NO: 1); and “PD-1” refers toPD-1 protein, polypeptide, or peptide, particularly human PD-1.

The inventors have further found that human PD-L1 is glycosylated atfour sites in the extracellular domain (ECD) at amino acid positionsN35, N192, N200 and/or N219 of the human PD-L1 protein, e.g., as setforth in SEQ ID NO: 1. The anti-glycPD-L1 antibodies as described maybind to one or more of these sites and, for example, may not bind toPD-L1 that has a mutation at one of more of these glycosylation sites(for example, a substitution of glutamine for asparagine within theglycosylation consensus sequence) and, thus, is not glycosylated at oneor more of these sites. Accordingly, in some embodiments, theanti-glycPD-L1 antibody specifically binds to one or more glycosylationmotifs in the PD-L1 glycopolypeptide or peptides thereof. In someembodiments, the anti-glycPD-L1 antibody binds to a PD-L1 glycopeptidewhich comprises a glycosylation motif and the adjacent peptide. In someembodiments, the anti-glycPD-L1 antibody binds to a peptide sequencethat is located near one or more of the glycosylation motifs in threedimensions. Accordingly, in embodiments, the anti-glycPD-L1 antibodyrecognizes and selectively binds to a conformational epitope ofglycosylated PD-L1. By way of example, in certain embodiments, theanti-glycPD-L1 antibody binds to glycosylated PD-L1 with a K_(d) of lessthan 85%, less than 80%, less than 75%, less than 70%, less than 65%,less than 60%, less than 55%, less than 50%, less than 45% of the K_(d)exhibited relative to unglycosylated PD-L1, but in embodiments, no morethan 5%, 10%, 15%, 20% or 25% of the K_(d) exhibited relative tounglycosylated PD-L1. It is to be understood that values in between aswell as equal to the foregoing K_(d) values are encompassed. In anembodiment the anti-glycPD-L1 antibody binds to glycosylated PD-L1 witha K_(d) of less than half of the K_(d) exhibited relative tounglycosylated PD-L1, but still exhibits the dual anti-glycosylatedPD-L1 function. In an embodiment, the anti-glycPD-L1 antibody binds toglycosylated PD-L1 protein with a K_(d) at least 5 times less than theK_(d) exhibited relative to unglycosylated PD-L1. In an embodiment, theanti-glycPD-L1 antibody binds to glycosylated PD-L1 protein with a K_(d)at least 10 times less than the K_(d) exhibited relative tounglycosylated PD-L1 protein. In certain embodiments, the anti-glycPD-L1antibody preferentially binds to cells expressing the WT glycosylatedPD-L1 with at least 1.5 times, 2, times, 3 times, 4 times, 5 times, 6times, 7 times, 8 times, 9 times, or 10 times greater frequency than tocells expressing unglycosylated PD-L1 as assayed in, for example, a cellflow cytometry assay in which the cells expressing WT PD-L1 andunglycosylated PD-L1 are mixed and differentially labeled, and thencontacted with the antibody to be assayed labeled with a detectablemarker, for example, as described in Example 5, and as measured, forexample, by the measured fluorescence intensity (MFI) for the twopopulations of cells when the antibody is directly or indirectlydetectable by a fluorescent label or marker, such as FITC. In anembodiment, the antibody is directly labeled with a fluorescent label ormarker, such as FITC. In an embodiment, the anti-glycPD-L1 antibodyselectively binds to glycosylated PD-L1 protein with an affinity of from5-20 nM, 5-10 nM, or 10-20 nM. In an embodiment, the antibody is amonoclonal antibody and, more preferably, a chimeric or humanized orhuman antibody. The terms “specifically bind” and “selectively bind” areused interchangeably herein.

Provided in a particular aspect is the anti-glycPD-L1 monoclonalantibody STM004, which has heavy and light chain variable domains havingamino acid sequences of SEQ ID NOs: 3 and 11, respectively, (matureV_(H) and V_(L) region amino acid sequences), or SEQ ID NOs: 86 and 88,respectively, which contain the signal peptide sequence, and antigenbinding portions thereof, and humanized and chimeric forms thereof.STM004 has been determined to bind an epitope on PD-L1 corresponding toamino acid residues at positions Y56, K62 and K75 of the human PD-L1amino acid sequence as set forth in SEQ ID NO: 1 herein, and is aconformational epitope. The portion of the human PD-L1 polypeptideencompassing the STM004 MAb epitope has the sequenceLDLAALIVYWEMEDKNIIQFVHGEEDLKVQH (SEQ ID NO: 93). As shown herein, theamino acid residues Y56, K62 and K75, which comprise the epitoperecognized by MAb STM004, i.e., are contacted by the mAb bound to PD-L1,are underlined. Provided herein are anti-glycPD-L1 antibodies thatcompete for binding to PD-L1 with STM004 MAb and/or bind to the sameepitope as STM004.

The nucleic acid (DNA) and corresponding amino acid sequences of theheavy and light chain variable (V) domains of the STM004 MAb are shownin Table 3 infra. SEQ ID NOs 2, 3, 10 and 11 are the nucleotide andamino acid sequences of the mature form of the heavy and light chainvariable domains (i.e., not having a signal peptide). Table 3 alsoprovides as SEQ ID NOs: 85-88 the nucleotide and amino acid sequences ofthe heavy and light chain variable domains in which the signal sequenceis represented in italicized font. Also shown in Table 3 are the Kabatand Chothia heavy and light chain V domain CDRs of STM004.

In an embodiment, the anti-glycPD-L1 antibody that specifically andpreferentially binds glycosylated PD-L1 comprises a V_(H) domain havingan amino acid sequence of SEQ ID NO: 3 and/or a V_(L) domain having anamino acid sequence of SEQ ID NO: 11. In an embodiment, theanti-glycPD-L1 antibody competes for specific binding to glycosylatedPD-L1 with an antibody comprising a V_(H) domain of SEQ ID NO: 3 and aV_(L) domain of SEQ ID NO: 11. In other embodiments, the anti-glycPD-L1antibody comprises a V_(H) domain that is at least 80%, 85%, 90%, 95%,96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:3 and/or a V_(L) domain that is at least 80%, 85%, 90%, 95%, 96%, 97%,98% or 99% identical to the amino acid sequence of SEQ ID NO: 11. Theseanti-glycPD-L1 antibodies may be chimeric antibodies and comprise ahuman constant domain, for example, from a human IgG1, IgG2, IgG3 orIgG4.

In an embodiment, the anti-glycPD-L1 antibody that specifically andpreferentially binds glycosylated PD-L1 comprises a V_(H) domaincomprising Chothia CDRs1-3 having amino acid sequences of SEQ ID NO: 4,SEQ ID NO: 6, and SEQ ID NO: 8, respectively, or comprising Kabat CDRs1-3 having amino acid sequences from SEQ ID NO: 5, SEQ ID NO: 7, SEQ IDNO: 9, respectively, or a combination thereof. In an embodiment, theanti-glycPD-L1 antibody competes for specific binding to glycosylatedPD-L1 with an antibody comprising a V_(H) domain comprising ChothiaCDRs1-3 having amino acid sequences of SEQ ID NO: 4, SEQ ID NO: 6, andSEQ ID NO: 8, respectively, or comprising Kabat CDRs 1-3 having aminoacid sequences of SEQ ID NO: 5, SEQ ID NO: 7, and SEQ ID NO: 9,respectively, or a combination thereof. In an embodiment, theanti-glycPD-L1 antibody that specifically and preferentially bindsglycosylated PD-L1 comprises a V_(L) domain comprising CDRs1-3 havingamino acid sequences of SEQ ID NO: 12, SEQ ID NO: 14, and SEQ ID NO: 16,respectively. In an embodiment, the anti-glycPD-L1 antibody competes forspecific binding to glycosylated PD-L1 with an antibody comprising aV_(L) domain comprising CDRs having amino acid sequences of SEQ ID NO:12, SEQ ID NO: 14, and SEQ ID NO: 16, respectively. In an embodiment,the anti-glycPD-L1 antibody comprises or competes for binding to anantibody that comprises a V_(H) domain comprising Chothia CDRs 1 to 3having amino acid sequences of SEQ ID NO: 4, SEQ ID NO: 6, and SEQ IDNO: 8, respectively, or comprising Kabat CDRs 1 to 3 having amino acidsequences from SEQ ID NO: 5, SEQ ID NO: 7, and SEQ ID NO: 9,respectively, and comprises a V_(L) domain comprising CDRs1-3 havingamino acid sequences of SEQ ID NO: 12, SEQ ID NO: 14, and SEQ ID NO: 16,respectively.

In other embodiments, the anti-glycPD-L1 antibody has a V_(H) domaincomprising CDRs H1, H2 and H3 with amino acid sequences that have 1, 2,3, 4, or 5 amino acid substitutions in 1, 2 or 3 of the CDRs having theamino acid sequences of SEQ ID NO: 4, SEQ ID NO: 6, and SEQ ID NO: 8,respectively, or of the CDRs having the amino acid sequences of SEQ IDNO: 5, SEQ ID NO: 7, and SEQ ID NO: 9, respectively. The anti-glycPD-L1antibody may have a V_(L) domain comprising CDRs L1, L2 and L3 withamino acid sequences that have 1, 2, 3, 4, or 5 amino acid substitutionsin 1, 2 or 3 CDRs having the amino acid sequences of SEQ ID NO: 12, SEQID NO: 14, and SEQ ID NO: 16, respectively. The anti-glycPD-L1 antibodymay have amino acid substitutions in CDRs for both the V_(H) and V_(L)domains. In some embodiments, the amino acid substitutions areconservative substitutions.

Preferably the foregoing antibodies have human framework regions, i.e.,are humanized forms of STM004, and optionally, comprise a human constantdomain, for example, from a human IgG1, IgG2, IgG3 or IgG4.

It will be appreciated by those skilled in the art that one or moreamino acid substitutions may be made in the CDRs and/or frameworkregions of a humanized antibody to improve binding affinity or otherparameter. In embodiments, the anti-glycPD-L1 antibody competes forspecific binding to glycosylated PD-L1 with an antibody comprising theabove-described V_(H) and V_(L) domains and the CDRs therein. Inembodiments, the anti-glycPD-L1 antibody binds to glycosylated PD-L1with a K_(d) less than half of the K_(d) exhibited by the antibody'sbinding to unglycosylated PD-L1. In an embodiment, the anti-glycPD-L1antibody binds to glycosylated PD-L1 protein with a K_(d) at least 5times less than the K_(d) exhibited relative to unglycosylated PD-L1. Inan embodiment, the anti-glycPD-L1 antibody binds to glycosylated PD-L1protein with a K_(d) at least 10 times less than the K_(d) exhibited bythe antibody's binding to unglycosylated PD-L1 protein. In anembodiment, in a cell flow cytometry binding assay as described inExample 5, the antibody exhibits binding as expressed as MFI to cellsexpressing WT PD-L1 that is 1.5 times, 2 times, 3, times, 4 times, 5times, 6 times, 7 times, 8 times, 9 times or 10 times greater than theMFI for binding to cells expressing unglycosylated PD-L1. In anembodiment, the antibody is directly or indirectly detectable by afluorescent label or marker. In an embodiment, the antibody is directlylabeled with a fluorescent label or marker, such as FITC. In anembodiment, the binding affinity of STM004 MAb, or chimeric or humanizedform thereof, for glycosylated PD-L1 is from 5-20 nM or from 5-10 nMinclusive of the lower and upper values. In an embodiment, the antibodyinhibits the interaction of PD-1 with PD-L1, and particularly inhibitsthe interaction of PD-1 expressed by effector T-cells with PD-L1,particularly, glycosylated PD-L1, expressed by tumor cells.

Provided in another particular aspect is the anti-glycPD-L1 monoclonalantibody STM115 which has heavy and light chain variable domains havingamino acid sequences of SEQ ID NOs: 19 and 27, respectively, (matureV_(H) and V_(L) region amino acid sequences), or SEQ ID NOs: 90 and 92,respectively, which contain the signal peptide sequence, and antigenbinding portions thereof, and humanized and chimeric forms thereof, thatspecifically bind glycosylated PD-L1. The nucleic acid (DNA) andcorresponding amino acid sequences of the heavy and light chain variable(V) domains of the STM115 MAb are shown in Table 3 infra. SEQ ID NOs 18,19, 26 and 27 are the nucleotide sequences encoding and the amino acidsequences of the mature form of the heavy and light chain variabledomains (i.e., not having a signal peptide). Table 3 also provides asSEQ ID NOs: 89-92 the nucleotide and amino acid sequences of the heavyand light chain variable domains including the signal sequence, wherethe signal sequence is represented in italicized font. Also shown inTable 3 are the Kabat and Chothia heavy and light chain V domain CDRs ofSTM115. Also provided are anti-glycPD-L1 antibodies that compete forbinding to PD-L1 with STM115 MAb and/or bind to the same epitope asSTM115.

In an embodiment, the anti-glycPD-L1 antibody that specifically andpreferentially binds glycosylated PD-L1 comprises a V_(H) domain havingthe amino acid sequence of SEQ ID NO: 19 and/or a V_(L) domain havingthe amino acid sequence of SEQ ID NO: 27. In an embodiment, theanti-glycPD-L1 antibody competes for specific binding to glycosylatedPD-L1 with an antibody comprising a V_(H) domain of SEQ ID NO: 19 and aV_(L) domain of SEQ ID NO: 27. In an embodiment, the anti-glycPD-L1antibody that specifically and preferentially binds glycosylated PD-L1comprises a V_(H) domain that is at least 80%, 85%, 90%, 95%, 96%, 97%,98% or 99% identical to the amino acid sequence of SEQ ID NO: 19 and/ora V_(L) domain that is at least 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99%identical to the amino acid sequence of SEQ ID NO: 27. Theseanti-glycPD-L1 antibodies may be chimeric antibodies and comprise ahuman constant domain, for example, from a human IgG1, IgG2, IgG3 orIgG4.

In an embodiment, the anti-glycPD-L1 antibody that specifically andpreferentially binds glycosylated PD-L1 comprises a V_(H) domaincomprising Chothia CDRs 1-3 having amino acid sequences of SEQ ID NO:20, SEQ ID NO: 22, and SEQ ID NO: 24, respectively, or comprising KabatCDRs 1-3 having amino acid sequences of SEQ ID NO: 21, SEQ ID NO: 23,and SEQ ID NO: 25, respectively, or a combination thereof. In anembodiment, the anti-glycPD-L1 antibody competes for specific binding toglycosylated PD-L1 with an antibody comprising a V_(H) domain comprisingChothia CDRs 1-3 having amino acid sequences of SEQ ID NO: 20, SEQ IDNO: 22, and SEQ ID NO: 24, respectively, or Kabat CDRs 1-3 having aminoacid sequences of SEQ ID NO: 21, SEQ ID NO: 23, and SEQ ID NO: 25,respectively, or a combination thereof. In an embodiment, theanti-glycPD-L1 antibody that specifically and preferentially bindsglycosylated PD-L1 comprises a V_(L) domain comprising CDRs 1-3 havingan amino acid sequences of SEQ ID NO: 28, SEQ ID NO: 30, and SEQ ID NO:32, respectively. In an embodiment, the anti-glycPD-L1 antibody competesfor specific binding to glycosylated PD-L1 with an antibody comprising aV_(L) domain comprising CDRs 1-3 having amino acid sequences of SEQ IDNO: 28, SEQ ID NO: 30, and SEQ ID NO: 32, respectively, or a combinationthereof. In an embodiment, the anti-glycPD-L1 antibody that specificallyand preferentially binds glycosylated PD-L1 comprises, or competes forbinding with, an antibody that comprises a V_(H) domain comprisingChothia CDRs 1-3 having amino acid sequences of SEQ ID NO: 20, SEQ IDNO: 22, and SEQ ID NO: 24, respectively, or comprising Kabat CDRs 1-3having amino acid sequences of SEQ ID NO: 21, SEQ ID NO: 23, and SEQ IDNO: 25, respectively, and comprises a V_(L) domain comprising CDRs 1-3having an amino acid sequences of SEQ ID NO: 28, SEQ ID NO: 30, and SEQID NO: 32, respectively.

Provided in certain embodiments are anti-glycPD-L1 antibodies which havea V_(H) domain comprising CDRs H1, H2 and H3 with amino acid sequencesthat have 1, 2, 3, 4, or 5 amino acid substitutions in 1, 2 or 3 CDRshaving the amino acid sequences of SEQ ID NO: 20, SEQ ID NO: 22, and SEQID NO: 24, respectively, or SEQ ID NO: 21, SEQ ID NO: 23, and SEQ ID NO:25, respectively. The anti-glycPD-L1 antibody also may have a V_(L)domain comprising CDRs L1, L2 and L3 with amino acid sequences that have1, 2, 3, 4, or 5 amino acid substitutions in 1, 2 or 3 CDRs having theamino acid sequences of SEQ ID NO: 28, SEQ ID NO: 30, and SEQ ID NO: 32,respectively. The anti-glycPD-L1 antibody may have amino acidsubstitutions in CDRs in both the V_(H) and V_(L) domains. In someembodiments, the amino acid substitutions are conservativesubstitutions.

In embodiments, the anti-glycPD-L1 antibody competes for specificbinding to glycosylated PD-L1 with an antibody comprising theabove-described V_(H) and V_(L) domains and the CDRs therein. Preferablythese antibodies have human framework regions, i.e., are humanized formsof STM115, and optionally, comprise a human constant domain, forexample, from a human IgG1, IgG2, IgG3 or IgG4. It will be appreciatedby those skilled in the art that one or more amino acid substitutionsmay be made in the CDRs or framework regions of a humanized antibody toimprove binding affinity or other parameter. In embodiments, theanti-glycPD-L1 antibody binds to glycosylated PD-L1 with a K_(d) lessthan half of the K_(d) exhibited relative to unglycosylated PD-L1. Inembodiments, the anti-glycPD-L1 antibody binds to glycosylated PD-L1with a K_(d) less than half of the K_(d) exhibited relative tounglycosylated PD-L1. In an embodiment, the anti-glycPD-L1 antibodybinds to glycosylated PD-L1 protein with a K_(d) at least 5 times lessthan the K_(d) exhibited by the antibody's binding to unglycosylatedPD-L1. In an embodiment, the anti-glycPD-L1 antibody binds toglycosylated PD-L1 protein with a K_(d) at least 10 times less than theKd exhibited by the antibody's binding to unglycosylated PD-L1 protein.In an embodiment, in a cell flow cytometry binding assay as described inExample 5, the antibody exhibits binding as expressed as MFI to cellsexpressing WT PD-L1 that is 1.5 times, 2 times, 3, times, 4 times, 5times, 6 times, 7 times, 8 times, 9 times or 10 times greater than theMFI for binding to cells expressing unglycosylated PD-L1. In anembodiment, the antibody is directly or indirectly detectable by afluorescent label or marker. In an embodiment, the antibody is directlylabeled with a fluorescent label or marker such as FITC. In anembodiment, the binding affinity of STM115 MAb, or binding domain orhumanized or chimeric form thereof, for glycosylated PD-L1 is from 5-20nM or from 5-10 nM inclusive of the lower and upper values. In anembodiment, the antibody inhibits the interaction of PD-1 with PD-L1,and particularly inhibits the interaction of PD-1 expressed by effectorT-cells with PD-L1, particularly, glycosylated PD-L1, expressed by tumorcells.

Provided in an aspect is an isolated anti-glycPD-L1 antibody that bindsglycosylated PD-L1 and competes or cross competes for specific bindingto glycosylated PD-L1 with MAb STM004 or MAb STM115 as described herein,when assayed via conventional competition methods. In an aspect, anisolated antibody that binds the same epitope as MAb STM004, MAb STM115,or an isolated anti-glycPD-L1 MAb as described herein, is provided.

Provided in another aspect is an isolated anti-glycPD-L1 antibody thatspecifically binds to an epitope within the PD-L1 sequenceLDLAALIVYWEMEDKNIIQFVHGEEDLKVQH (SEQ ID NO: 93).

Provided in a certain embodiment is an isolated anti-glycPD-L1 antibodythat binds an epitope that comprises amino acid residues Y56, K62 andK75 of the human PD-L1 protein of SEQ ID NO: 1. In an aspect, anisolated anti-glycPD-L1 antibody is provided that specifically bindsglycosylated human PD-L1, such that when bound to human PD-L1, theantibody binds at least one of the following amino acid residues: Y56,K62, or K75 of SEQ ID NO: 1, wherein the antibody inhibits binding ofhuman PD-1 binding to human glycosylated PD-L1.

Provided in another embodiment is an isolated anti-glycPD-L1 antibodythat binds an epitope that comprises amino acid residues K62, H69 andK75 of the human PD-L1 protein of SEQ ID NO: 1. In an aspect, anisolated anti-glycPD-L1 antibody is provided that specifically bindsglycosylated human PD-L1, such that when bound to human PD-L1, theantibody binds at least one of the following amino acid residues: K62,H69, or K75 of SEQ ID NO: 1, wherein the antibody inhibits binding ofhuman PD-1 binding to human glycosylated PD-L1. In embodiments, theanti-glycPD-L1 antibody contacts at least two, at least three, or fourof the amino acid residues comprising the epitope region(s) of PD-L1.

In another aspect, an isolated antibody is provided that specificallybinds glycosylated human PD-L1, such that when bound to human PD-L1, theantibody binds at least one amino acid within the amino acid region fromL48 to H78 of SEQ ID NO: 1. In an aspect, an isolated antibody isprovided that specifically binds glycosylated human PD-L1, such thatwhen bound to human PD-L1, the monoclonal antibody binds the followinggroup of amino acid residues: Y56, K62, K75 within the amino acid regionfrom L48 to H78 of SEQ ID NO: 1; wherein the monoclonal antibodyinhibits binding of PD-1 to PD-L1, particularly, human PD-1 to humanglycosylated PD-L1. In another aspect, an isolated antibody is providedthat specifically binds glycosylated human PD-L1, such that when boundto human PD-L1, the antibody binds at least one amino acid within theamino acid region from D61 to H78 of SEQ ID NO: 1. In an aspect, anisolated antibody is provided that specifically binds glycosylated humanPD-L1, such that when bound to human PD-L1, the monoclonal antibodybinds the following group of amino acid residues: K62, H69 and K75within the amino acid region from D61 to H78 of SEQ ID NO: 1; whereinthe monoclonal antibody inhibits binding of PD-1 to PD-L1, particularly,human PD-1 to human glycosylated PD-L1.

Provided in another aspect is an isolated anti-glycPD-L1 antibody thatspecifically binds glycosylated human PD-L1 protein such that when boundto human PD-L1, the antibody binds within the amino acid region L48-H78or within the amino acid region D61-H78 of the human PD-L1 protein (SEQID NO: 1).

In another aspect, an isolated antibody or a binding fragment thereof isprovided that specifically and preferentially binds glycosylated humanPD-L1 versus non-glycosylated human PD-L1, which antibody comprises (a)a V_(H) domain comprising a Kabat CDR1 having an amino acid sequence ofSEQ ID NO: 5 or SEQ ID NO: 21 or a Chothia CDR 1 having an amino acidsequence of SEQ ID NO: 4 or SEQ ID NO: 20; a Kabat CDR2 having an aminoacid sequence of SEQ ID NO: 7 or SEQ ID NO: 23 or a Chothia CDR2 havingan amino acid sequence of SEQ ID NO: 6 or SEQ ID NO: 22; and a KabatCDR3 having an amino acid sequence of SEQ ID NO: 9 or SEQ ID NO: 25 or aChothia CDR 3 having an amino acid sequence of SEQ ID NO: 8 or SEQ IDNO: 24; and (b) a V_(L) domain comprising a CDR1 having an amino acidsequence of SEQ ID NO: 12 or SEQ ID NO: 28; a CDR2 having an amino acidsequence of SEQ ID NO: 14 or SEQ ID NO: 30; and a CDR3 having an aminoacid sequence of SEQ ID NO: 16 or SEQ ID NO: 32, wherein the antibodyinhibits a human PD-1 and human PD-L1 interaction. In a preferredembodiment, the antibody is a humanized antibody having human antibodyframework and, optionally, a human antibody constant domain.

Provided in another aspect is an isolated nucleotide molecule comprisinga nucleotide sequence selected from SEQ ID NOs: 2 or 18 and/or anucleotide sequence selected from SEQ ID NO: 10, or 26, respectively. Anembodiment provides an isolated nucleotide sequence encoding ananti-glycPD-L1 V_(H) domain, which nucleotide sequence is at least90-98% identical to the nucleotide sequence of SEQ ID NOs: 2 or 18.Another embodiment provides an isolated nucleotide sequence encoding ananti-glycPD-L1 V_(L) domain, which nucleotide sequence is at least90-98% identical to the nucleotide sequence of SEQ ID NOs: 19 or 26. Inembodiments, the nucleotide sequences encoding the V_(H) and/or theV_(L) domains are 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, ormore identical to SEQ ID NOs: 2 or 18, or SEQ ID NOs: 10 or 26,respectively. These nucleotide sequences encode V_(H) domains and V_(L)domains that at least in the context of a bivalent antibody,specifically bind to glycosylated PD-L1.

In certain aspects, the anti-glycPD-L1 antibody is an IgG, IgM, IgA, anisotype thereof, such as IgG1, IgG2a, IgG2b, IgG4, or an antigen bindingfragment thereof. In other aspects, anti-glycPD-L1 antibody is an Fab′,a F(ab′)2, a F(ab′)3, a monovalent scFv, a bivalent scFv, a bispecificantibody, a bispecific scFv, or a single domain antibody. In someaspects, the anti-glycPD-L1 antibody is a human antibody or a humanizedantibody. In an aspect, the anti-glycPD-L1 antibody is recombinantlyproduced. In further aspects, the anti-glycPD-L1 antibody is conjugatedto an imaging agent, a chemotherapeutic agent, a toxin, or aradionuclide.

In an aspect, a composition comprising an anti-glycPD-L1 antibody (e.g.,an antibody that selectively and preferentially binds to glycosylatedPD-L1 relative to unglycosylated PD-L1) in a pharmaceutically acceptablecarrier or medium is provided.

Provided in a further aspect is an isolated polypeptide comprising apeptide of at least 7 (e.g., at least 8, 9, 10, 11, 12, 13, 14, 15, 16,17, 18, 19, 20 or more) contiguous amino acids of human PD-L1 comprisingat least one amino acid corresponding to position N35, N192, N200 orN219 within the extracellular domain (ECD) of human PD-L1. In anembodiment, the isolated polypeptide comprises a peptide of at least 7(e.g., at least 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 ormore) contiguous amino acids of human PD-L1, comprising at least oneamino acid corresponding to position N35, N192, N200 or N219 of humanPD-L1, in which at least one of the amino acids corresponding toposition N35, N192, N200 or N219 of PD-L1 is glycosylated. In anembodiment, the isolated polypeptide is fused or conjugated to animmunogenic polypeptide (e.g., keyhole limpet hemocyanin, KLH). Incertain aspects, the polypeptide further comprises a cysteine (Cys)residue at its amino (N)- or carboxy (C)-terminus. For example, thepolypeptide may be conjugated to an immunogenic polypeptide by adisulfide linkage at the Cys residue. In a particular embodiment, thePD-L1 peptide comprising at least one amino acid residue glycosylated ata position corresponding to position N35, N192, N200 or N219 of humanPD-L1 is used as an immunogen to generate anti-glycPD-L1 antibodies.

In a further aspect, a composition is provided comprising a polypeptideof at least 7 (e.g., at least 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,19, 20 or more) contiguous amino acids of human PD-L1 comprising atleast one amino acid corresponding to position N35, N192, N200 or N219within the ECD of human PD-L1, wherein at least one of said amino acidscorresponding to position N35, N192, N200 or N219 of PD-L1 isglycosylated, wherein the polypeptide is formulated in apharmaceutically acceptable carrier, diluent, excipient, or vehicle.

In yet a further aspect, an immunogenic composition is providedcomprising a polypeptide of at least 7 contiguous amino acids of humanPD-L1, which comprises at least one amino acid corresponding to positionN35, N192, N200 or N219 within the ECD of the human PD-L1 polypeptide,wherein at least one of the amino acids corresponding to position N35,N192, N200 or N219 within the ECD of the PD-L1 polypeptide isglycosylated, and wherein the polypeptide is formulated in apharmaceutically acceptable carrier, diluent, excipient, or vehicle. Insome aspects, the immunogenic composition further comprises an adjuvant,such as alum or Freund's adjuvant.

Provided in a further aspect is a method for treating a subject in need,such as a subject with a cancer, which comprises administering aneffective amount of an anti-glycPD-L1 antibody to the subject. Inspecific embodiments, the anti-glycPD-L1 antibody is a humanized orchimeric form of MAb STM004 or MAb STM115 or another anti-glycPD-L1antibody as described herein. In certain embodiments, the anti-glycPD-L1antibody is an antibody that competes for binding to glycosylated PD-L1with MAb STM004, MAb STM115, or an anti-glycPD-L1 antibody as describedherein. In an embodiment, a method of treating a cancer in a subject inneed thereof, is provided in which the method comprises administering aneffective amount of an antibody as described herein to the subject.Administration of the anti-glycPD-L1 antibody blocks theimmune-inhibitory activity of PD-1, thus promoting anti-cancer activityin T cells, resulting in tumor cell killing.

In nonlimiting embodiments, the cancer, disease or pathology to betreated in the subject is a breast cancer, lung cancer, head & neckcancer, prostate cancer, esophageal cancer, tracheal cancer, skin cancerbrain cancer, liver cancer, bladder cancer, stomach cancer, pancreaticcancer, gall bladder cancer, ovarian cancer, uterine cancer, cervicalcancer, testicular cancer, colon cancer, rectal cancer or skin cancer.In certain embodiments, the cancer to be treated is an adrenal cancer,an anal cancer, a bile duct cancer, a bladder cancer, a bone cancer, abrain/CNS tumor in an adult, a brain/CNS tumor in a child, a breastcancer, a breast cancer in a man, cancer in an adolescent, cancer in achild, cancer in a young adult, cancer of unknown primary, Castlemandisease, cervical cancer, colon/rectum cancer, endometrial cancer,esophagus cancer, Ewing family tumor, eye cancer, gallbladder cancer,gastrointestinal carcinoid tumor, gastrointestinal stromal tumor (GIST),gestational trophoblastic disease, Hodgkin disease, Kaposi sarcoma,kidney cancer, laryngeal or hypopharyngeal cancer, leukemia (e.g., adultacute lymphocytic (ALL), acute myeloid (AML), chronic lymphocytic (CLL),chronic myeloid (CML), chronic myelomonocytic (CMML), childhoodleukemia), liver cancer, lung cancer (e.g., non-small cell, small cell),lung carcinoid tumor, lymphoma, lymphoma of the skin, malignantmesothelioma, multiple myeloma, myelodysplastic syndrome, naval cavitycancer, paranasal sinus cancer, nasopharyngeal cancer, neuroblastoma,non-Hodgkin lymphoma, non-Hodgkin lymphoma in a child, oral cavitycancer, oropharyngeal cancer, osteosarcoma, ovarian cancer, pancreaticcancer, penile cancer, pituitary tumors, prostate cancer,retinoblastoma, rhabdomyosarcoma, salivary gland cancer, sarcoma (e.g.,adult soft tissue cancer), skin cancer (e.g., basal and squamous cell,melanoma, merkel cell), small intestine cancer, stomach cancer,testicular cancer, thymus cancer, thyroid cancer, uterine sarcoma,vaginal cancer, vulvar cancer, Waldenstrom macroglobulinemia, or Wilmstumor.

In certain embodiments, the cancer is positive for PD-L1 and a secondcancer marker, for example EGFR. Such cancers may be treated with acombination of anti-glycPD-L1 antibody and an anti-cancer agent thattargets the cancer marker, for example, a receptor tyrosine kinaseinhibitor, e.g., an EGFR tyrosine kinase inhibitor, such as gefitinib.

In certain aspects, the anti-glycPD-L1 antibody is in a pharmaceuticallyacceptable composition. In further aspects, the antibody is administeredsystemically. In particular aspects, the antibody is administeredintravenously, intradermally, intratumorally, intramuscularly,intraperitoneally, subcutaneously, intrathecally, or locally. In otheraspects, one or more than one anti-glycPD-L1 antibody may beco-administered to a subject in need. Co-administration of antibodiesmay involve the administration of one antibody before, after, orconcurrently with another antibody.

In an aspect, a method of treating a subject who has a cancer or tumor,particularly a cancer or tumor that expresses PD-L1 or highly expressesPD-L1 on the cancer or tumor cell surface is provided. Such a methodcomprises administering to the subject in need thereof an effectiveamount of an anti-glycPD-L1 antibody according to the presentembodiments to inhibit or block the interaction of PD-L1 with PD-1 andprevent immunosuppression and promote killing of the cancer or tumorcells by the subject's effector T lymphocytes. In embodiments, theanti-glycPD-L1 antibody is a humanized or chimeric form of STM004 orSTM115, or an antibody that competes with one or both of theseantibodies for selectively binding PD-L1 versus non-glycosylated PD-L1.

Certain embodiments provide methods of treating cancer in a subjectcomprises administering at least two different anti-glycPD-L1antibodies, preferably resulting in a greater therapeutic efficacy thanone anti-glycPD-L1 antibody.

In some aspects, the methods further comprise administering at least asecond anticancer therapy or drug to the subject who is receivingtreatment with an anti-glycPD-L1 antibody according to the embodiments.The second anticancer therapy may constitute, without limitation, asurgical therapy, chemotherapy, radiation therapy, cryotherapy, hormonaltherapy, immunotherapy or cytokine therapy. The second anticancer drugis also not intended to be limited and will be able to be practically orempirically determined by the clinician, medical professional (e.g.,oncologist) skilled in the art. As will be appreciated by one havingskill in the art, the administration of at least a second anticancertherapy or drug may occur before, after, or simultaneously with theadministration of an antibody of the embodiments.

Provided in another aspect is a method of determining if a patient withcancer is likely to benefit from treatment with an agent that blocksbinding of PD-L1 with PD-1, the method comprising testing for thepresence of glycosylated PD-L1 on cells derived from a sample of thepatient's cancer cells using an antibody that preferentially bindsglycosylated PD-L1; and administering to the patient an effective amountof an agent that prevents binding of PD-L1 to PD-1 if subject's cancercells are found to be positive for the expression of glycosylated PD-L1protein. In an embodiment, the agent that prevents binding of PD-L1 toPD-1 is an anti-glycPD-L1 antibody, such as described herein, ananti-PD-1 antibody, or a combination thereof. In an embodiment, theanti-glycPD-L1 antibody and/or anti-PD-1 antibody is administered incombination with another anti-cancer drug or therapeutic. In anembodiment, an anti-glycPD-L1 antibody is administered in combinationwith another anti-glycPD-L1 antibody, such as described herein. In anembodiment, the method further involves obtaining the cancer cell samplefrom the patient.

Provided in yet another aspect is a method for assessing glycosylation,N-linked glycosylation, or N-glycosylation of PD-L1 protein in abiological sample, in which the method comprises contacting the samplewith an antibody as described herein (e.g., an antibody thatpreferentially binds to glycosylated PD-L1 relative to unglycosylatedPD-L1, such as STM004 or STM115 herein). In some aspects, the method isan in vitro method or assay. In certain aspects, the biological sampleis cell sample, a tissue sample, a body fluid (e.g., plasma, serum,blood, urine, sputum, lymph, ascites fluid, intraperitoneal fluid,cerebral or spinal fluid, and the like). In particular embodiments, thesample is a cell sample or a cell sample from a tumor or cancer obtainedfrom a subject having a cancer or tumor. Such a cancer or tumor cellsample may be assayed for glycosylated PD-L1 on the cancer or tumor cellsurface using the anti-glycPD-L1 antibodies as described herein,particularly to determine that, if glycosylated PD-L1 is present on thesubject's cancer or tumor cells, then the cells would likely beappropriate targets for treatment with the anti-glycPD-L1 antibodies asdescribed.

Provided in another aspect is a method of making an antibody in whichthe method comprises administering to a subject (e.g., an animal) apolypeptide according to the embodiments (e.g., a polypeptide comprisinga fragment of at least 7 contiguous amino acids of human PD-L1comprising at least one amino acid corresponding to position N35, N192,N200 or N219 of human PD-L1, wherein at least one of said amino acidscorresponding to position N35, N192, N200 or N219 of PD-L1 isglycosylated) and isolating the antibody from the subject. By way ofexample, the animal can be a non-human primate, mouse, rat, rabbit,goat, or a human. In certain aspects a method further comprisesidentifying the CDRs of the antibody and humanizing the sequences (i.e.,framework sequences) surrounding the CDRs to produce a humanizedantibody using methods and procedures known in the art. In still furtheraspects, the method comprises recombinantly expressing the humanizedantibody. Thus, in a further embodiment, there is provided an isolatedantibody produced by the foregoing method. Thus, in some embodiments,there is provided an isolated antibody that selectively binds to anepitope, such as a conformational epitope, of a polypeptide of theembodiments (e.g., a polypeptide comprising a fragment of at least 7contiguous amino acids of human PD-L1 comprising at least one amino acidcorresponding to position N35, N192, N200 or N219 of human PD-L1,wherein at least one of said amino acids corresponding to position N35,N192, N200 or N219 of PD-L1 is glycosylated) relative to unglycosylatedPD-L1. Provided in an embodiment is a method for immunizing a subject toproduce an immune response, e.g., an antibody response directed againstan antigen, comprising administering an effective amount of apolypeptide of the embodiments (e.g., a glycosylated PD-L1 polypeptide)as immunogenic antigen to the subject.

Other aspects, features and advantages of the described embodiments willbecome apparent from the following detailed description and illustrativeexamples.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and areincluded to further demonstrate certain aspects of the embodimentsdescribed herein without being limiting.

FIGS. 1A-1H. PD-L1 is Glycosylated in Cancer Cells. 1A. Expression ofPD-L1 protein in primary breast cancer patient samples. Western blotanalysis of PD-L1 in representative breast cancer patient samples. 1B.Western blot analysis of PD-L1 in four representative breast cancer celllines, four melanoma cell lines, three lung cancer cell lines and threecolon cancer cell lines. 1C. Western blot analysis of PD-L1 expressionin shCTRL and two independent shPD-L1 stable clones of A431 cells. PD-L1was transiently transfected into the shPD-L1#5 clone. 1D. Glycoproteinstaining of purified PD-L1 protein with or without PNGase F treatment.The Coomassie blue stained panel represents the total amount of PD-L1protein. The upper bands which appear in lanes 4 and 5 are from theloading of PNGase F. (−) Ctrl, a control for non-glycoprotein; (+) Ctrl,a control for glycoprotein. 1E. Glycosylation pattern of PD-L1-GFP,HA-PD-L1, and PD-L1-Flag proteins. Cell lysates were treated with PNGaseF and Endo H and analyzed by Western blot. 1F. GFP-tagged PD-L1 fulllength (WT), extracellular domain (ECD), or intracellular domain (ICD)was transiently expressed in 293T cells. Cells were then treated with orwithout 5 μg/ml tunicamycin (TM) overnight. Protein expression of PD-L1was examined using Western blot. 1G. Schematic diagram of arepresentative PD-L1 protein expression construct as used in theexperimental studies described herein, showing the full-length PD-L1protein and its component extracellular domain (ECD), intracellulardomain (ICD), signal peptide (SP); transmembrane domain (TM). In thediagram, four N-glycosylation sites (NXT motifs) in the ECD domain ofPD-L1 are shown in red. The numbers indicate the positions of the aminoacid residues in the PD-L1 polypeptide. 1H. Western blot analysis of theprotein expression pattern of PD-L1 WT and glycosylation mutants (NQmutants) of PD-L1. Lane 14 indicates non-glycosylated, wild-type (WT)PD-L1 treated overnight with tunicamycin (TM). In the figures, the blackcircles indicate glycosylated PD-L1, and the black arrowheads indicatenon-glycosylated PD-L1.

FIGS. 2A-2D. Expression of PD-L1 Protein in Cancer Cells. A. Westernblot analysis of PD-L1 in lung cancer cells. B. Western blot analysis ofPD-L1 in colon cancer cells. C. Western blot analysis of PD-L1 in breastcancer cells. D. Western blot analysis of PD-L1 in ovarian cancer cells.Black circles=glycosylated PD-L1; arrowheads=, non-glycosylated PD-L1.

FIGS. 3A-3D. PD-L1 is Glycosylated in Cancer Cells. A. Western blotanalysis of PD-L1 in cancer cells using different anti-PD-L1 antibodies.Four BLBC cell lines, HCC1937, SUM149, MB-231 and BT20, and two non-BLBCcell lines, MB-483 and MB-474 were selected to analyze the expression ofPD-L1 using different antibodies. B. Western blot analysis of PD-L1 inshCTRL and two independent shPD-L1 stable clones of MDA-MB-231 and A431cells. C. Schematic diagram of dual-expression construct for Flag-PD-L1and shRNA of PD-L1. D. Glycosylation pattern of PD-L1 protein inMDA-MB-231 and A431 cells. Cell lysates were treated with PNGase F andanalyzed by Western blot. Black circle=glycosylated PD-L1;arrowhead=non-glycosylated PD-L1.

FIGS. 4A-4E. Expression of Glycosylated and Non-glycosylated PD-L1Protein. A. Western blot analysis of PD-L1-Myc, PD-L1-Flag, and HA-PD-L1proteins in tunicamycin (TM) treated cells. B. Western blot analysis ofPD-L1-GFP-WT, PD-L1-GFP-ECD and PD-L1-GFP-ICD proteins in tunicamycin(TM) treated or untreated cells. C. Western blot analysis of PD-L1-Myc,PD-L1-Flag, HA-PD-L1, PD-L1-GFP-WT, PD-L1-GFP-ECD and PD-L1-GFP-ICDproteins in tunicamycin (TM) treated cells. The intensity ofglycosylated PD-L1 protein (black bars) or non-glycosylated PD-L1protein (red bars) was determined by a densitometry quantification (inbar graph below Western blot analysis). D. The mean of the intensity ofglycosylated PD-L1 protein (black bar) or non-glycosylated PD-L1 protein(red bar) obtained from the bar graph shown in (c) above. Error barsrepresent SD. E. Glycosylation pattern of PD-L1 protein in PD-L1expressing HEK 293T cells. Cell lysates were treated with or withoutPNGase F or O-glycosidase and analyzed by Western blot. Blackcircle=glycosylated PD-L1; arrowhead=non-glycosylated PD-L1. Asappreciated by one skilled in the art, tunicamycin is a nucleosideantibiotic that inhibits N-linked glycosylation of proteins. (Heifetz,A. et al., 1979, Biochemistry, 18:2186-2192).

FIGS. 5A and 5B. N-glycosylation Sites of PD-L1 Protein. A sequencealignment of the PD-L1 amino acid sequences from different species. FourNXT motifs, N35, N192, N200, and N219 are boxed and presented in red,and two non-NXT motifs, N63 and N204 are presented in green. Redbox=conserved NXT motif. FIG. 5A: Consensus sequence (SEQ ID NO: 74);Q9NZQ7 HUMAN (SEQ ID NO: 75); Q9EP73_MOUSE (SEQ ID NO: 76); D4AE25_RAT(SEQ ID NO: 77); C5NU11_BOVINE (SEQ ID NO: 78); Q4QTK1_PIG (SEQ ID NO:79); and F7DZ76_HORSE (SEQ ID NO: 80). FIG. 5B: Consensus sequence (SEQID NO: 94); Q9NZQ7 HUMAN (SEQ ID NO: 95); Q9EP73 MOUSE (SEQ ID NO: 96);D4AE25 RAT (SEQ ID NO: 97); C5NU11_BOVINE (SEQ ID NO: 98); Q4QTK1_PIG(SEQ ID NO: 99); and F7DZ76_HORSE (SEQ ID NO: 100).

FIGS. 6A-6H. LC-MS/MS-based Identification of N-glycopeptides.LC-MS/MS-based identification of N-glycopeptides corresponding to eachof the four N-glycosylation sites, N35 (A and E), N192 (B and F), N200(C and G), and N219 (D and H) of PD-L1 from HEK 293 cells. The LC-MSprofiles (A-D) are shown as spectra averaged over a period of elutiontime (as labeled in figures) when a representative subset of glycoformswere detected. For each N-glycosylation site, one representative HCD MS²spectrum (E-H) is shown to exemplify its identification based ondetection of y1 ion (tryptic peptide backbone carrying the GlcNAcattached to the N-glycosylated Asn), along with the b and y ionsdefining its peptide sequence. The cartoon symbols used for the glycans(see inset) conform to the standard representation recommended by theConsortium for Functional Glycomics: Additional Hex and HexNAc weretentatively assigned as either lacNAc (Gal-GlcNAc) or lacdiNAc(GalNAc-GlcNAc) extension from the trimannosyl core (Man₃-GlcNAc₂),which can either be core fucosylated or not. The sequences depicted inFIGS. 6E-6H are set forth in SEQ ID NOs: 81-84, respectively.

FIGS. 7A-7E. Glycosylation of PD-L1 is Required for CancerCell-associated Immunosuppression. A. Flow cytometry measuring theinteraction of membrane bound PD-1 and PD-L1 WT or PD-L1 4NQ mutantprotein expressed on BT549 cells. Cells were pretreated with MG132 priorto experiment. B. Time lapse microscopy image showing the dynamicinteraction between PD-L1 and PD-1 at the last time point. Redfluorescent (nuclear restricted RFP) and green fluorescent (greenfluorescent labeled PD-1/Fc protein) merged images (20×) of PD-L1 WT or4NQ expressing cells. The kinetic graph at right in B. shows thequantitative binding of the PD-1/Fc protein to PD-L1 WT or PD-L1 4NQprotein expressed on BT549 cells at every hour time point. C. Tcell-meditated tumor cell killing (TTK) assay involving PD-L1 WT or 4NQPD-L1 protein expressed on BT549 cells. Representative phase, redfluorescent (nuclear restricted RFP), and/or green fluorescent (NucView™488 Caspase 3/7 substrate) merged images (10×) of PD-L1 WT or 4NQexpressing cells, and PD-1-expressing T cell co-cultures in the presenceof Caspase 3/7 substrate at 96 hours. T cells were activated withanti-CD3 antibody (100 ng/ml) and IL-2 (10 ng/ml). Green fluorescentcells were counted as dead cells. The quantitative ratio of dead cellsversus total cells associated with PD-L1 WT or PD-L1 4NQ protein ispresented in the bar graph at the right of the images. D. Tumor growthin BALB/c mice bearing tumors derived from injected 4T1 cells thatexpressed either PD-L1 WT or PD-L1 4NQ mutant protein. Tumor growth of4T1-luc cells was shown in vivo by bioluminescence imaging using IVIS100(at left in D). At right in D: Box plots showing the tumor volume andphotos showing tumor size in mice bearing tumors derived from 4T1 cellsexpressing PD-L1 WT versus PD-L1 4NQ proteins. Tumors were measured anddissected at the endpoint. n=8 mice per group (right). E. Intracellularcytokine staining of IFNγ in CD8+ CD3+ T cell populations. Significancewas determined by two-way ANOVA, with *p<0.05 and **p<0.001; n=7 miceper group. * indicates statistically significant by Student's t test.All error bars are expressed as mean±SD of 3 independent experiments.

FIGS. 8A-8C. Schematic Diagram of Glycosylated and Non-glycosylatedForms of the PD-L1 Protein and Western Blot Analyses. A. Schematicdepiction of wild type, glycosylated PD-L1 protein (PD-L1 WT) and fourPD-L1 protein variants, each having one glycosylated amino acid residueand three non-glycosylated amino acid residues out of the fourN-glycosylation sites of the PD-L1 protein (N35/3NQ; N192/3NQ; N200/3NQ;and N219/3NQ). The amino acids designated in black representglycosylated residues; the amino acid sites shown in red arenon-glycosylated in the variant PD-L1 proteins. B. Stable clones of BT549 expressing N35/3NQ, N192/3NQ, N200/3NQ and N219/3NQ forms of thePD-L1 protein were generated. Some of the anti-glycPD-L1 antibodiesshowed a greater level of binding to certain of the PD-L1 glycosylationvariants versus others as determined by Western blot analysis,demonstrating that those MAbs were site specific. As shown in B, forexample, MAb STM004 recognized and bound the N35/3NQ PD-L1 variant,indicating that this monoclonal antibody bound to the N35 region ofglycosylated PD-L1. C. shows the results of a Western blot of the STM004MAb binding to lysates of liver cancer cell lines.

FIG. 9. Anti-glycPD-L1 Antibodies Enhance Tumor Cell Killing by T Cells.The STM004 MAb was used in different amounts in a cellular cytotoxicityassay as described in Example 8 to assess the cytotoxicity ofPBMC-derived T-cells against tumor cells (BT549). FIG. 9 shows celldeath of BT549 (RFP PD-L1 (WT) cells treated with MAb STM004 in realtime. In FIG. 9, the bottom graph (solid blue squares) represents thecontrol (no T cells from PBMCs); the solid red circles represent a NoAntibody control; the solid black squares represent 20 μg/ml of theSTM004 MAb used in the assay; and the solid brown circles represent 40μg/ml of the STM004 MAb used in the assay. As observed from FIG. 9, adose proportional killing of PD-L1 bearing tumor cells over time isdemonstrated.

FIGS. 10A and 10B. Binding Assays. FIGS. 10A and 10B show the results ofa binding assay as described in Example 9, in which the STM004 MAb (FIG.10A) is seen to block binding of PD-1 to BT549 target cells expressingWT PD-L1 in a dose dependent manner versus assay controls, No PD-1/Fc;No Ab; mIgG Ab control (FIG. 10B).

Other aspects, features and advantages of the described embodiments willbecome apparent from the following detailed description and illustrativeexamples.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The extracellular interaction between programmed death ligand-1 protein(PD-L1) expressed on tumor cells and programmed death-1 protein (PD-1)expressed on immune effector cells, e.g., T-cells, has a marked impacton tumor-associated immune escape. Despite the clinical success ofimmune checkpoint blockade using anti-PD-1 or anti-PD-L1 antibodies, theregulatory mechanisms and structural features underlying the PD-L1 andPD-1 interaction remain largely unknown. In accordance with the findingsdescribed herein, it has been demonstrated that N-linked glycosylationof PD-L1 facilitates and enhances PD-L1 binding to PD-1, which promotesthe suppression of T cell-mediated immune response. Conversely, it hasbeen newly found that aberrant glycosylation, or a lack of N-linkedglycosylation, such as from partial or complete deglycosylation of thePD-L1 polypeptide expressed on tumor cells, adversely affects, e.g.,weakens or disrupts, the PD-L1/PD-1 interaction, which, in turn,inhibits immunosuppression and promotes effector T-cell cytotoxicactivity and killing of tumor cells. In addition, because the survivalof patients whose tumors express highly glycosylated PD-L1 is poor,glycosylated PD-L1 is recognized, based on the findings herein, as aneffective therapeutic target for cancer treatment. Provided anddescribed herein are cancer therapeutics, such as anti-glycPD-L1antibodies, that specifically and preferentially bind and interact withglycosylated PD-L1, as compared to unglycosylated PD-L1 to disrupt aglycosylated PD-L1/PD-1 interaction, inhibit immunosuppression andpromote T-cell effector function so as to treat cancer. Tumor treatmentwith the anti-glycosylated PD-L1 antibodies as described herein offersenhanced immunosuppression inhibitory effects relative to anti-PD-L1antibodies that are not specific for glycosylated forms of PD-L1. Inembodiments, the anti-glycPD-L1 antibodies are monoclonal antibodies,designated “MAbs” herein.

The Examples described herein provide experimental results showing asignificant difference, e.g., 2-3 fold, in binding of glycosylated PD-L1versus non-glycosylated PD-L1 by the anti-glycPD-L1 antibodies asdescribed herein. In embodiments, the anti-glycPD-L 1 antibodies exhibita binding affinity for glycosylated PD-L1 in the nanomolar range, e.g.,from about 5-20 nM or about 10-20 nM, relative to non-glycosylated PD-L1

Definitions

As used herein, the term “a” or “an” may mean one or more.

As used herein, the term “or” means “and/or” unless explicitly indicatedto refer to alternatives only or the alternatives are mutuallyexclusive, although the disclosure supports a definition that refers toonly alternatives and “and/or.”

As used herein, the term “another” means at least a second or more.

As used herein, the term “about” is used to indicate that a valueincludes the inherent variation of error for the device, the methodbeing employed to determine the value, or the variation that existsamong the study subjects.

As used herein, the term “programmed death ligand-1” or “PD-L1” refersto a polypeptide (the terms “polypeptide” and “protein” are usedinterchangeably herein) or any native PD-L1 from any vertebrate source,including mammals such as primates (e.g., humans, cynomolgus monkey(cyno)), dogs, and rodents (e.g., mice and rats), unless otherwiseindicated, and, in certain embodiments, included various PD-L1 isoforms,related PD-L1 polypeptides, including SNP variants thereof.

An exemplary amino acid sequence of human PD-L1 (UniProtKB/Swiss-Prot:Q9NZQ7.1; GI:83287884), is provided below: MRIFAVFIFM TYWHLLNAFTVTVPKDLYVV EYGSNMTIEC KFPVEKQLDL AALIVYWEME DKNIIQFVHG EEDLKVQHSSYRQRARLLKD QLSLGNAALQ ITDVKLQDAG VYRCMISYGG ADYKRITVKV NAPYNKINQRILVVDPVTSE HELTCQAEGY PKAEVIWTSS DHQVLSGKTT TTNSKREEKL FNVTSTLRINTTTNEIFYCT FRRLDPEENH TAELVIPELP LAHPPNERTH LVILGAILLC LGVALTFIFRLRKGRMMDVK KCGIQDTNSK KQSDTHLEET (SEQ ID NO: 1). In SEQ ID NO: 1, theamino terminal amino acids 1-18 constitute the signal sequence of thehuman PD-L1 protein. Accordingly, the mature human PD-L1 proteinconsists of amino acids 19-290 of SEQ ID NO: 1.

Abbreviations for the amino acid residues that comprise polypeptides andpeptides described herein, and conservative substitutions for theseamino acid residues are shown in Table 1 below. A polypeptide thatcontains one or more conservative amino acid substitutions or aconservatively modified variant of a polypeptide described herein refersto a polypeptide in which the original or naturally occurring aminoacids are substituted with other amino acids having similarcharacteristics, for example, similar charge,hydrophobicity/hydrophilicity, side-chain size, backbone conformation,structure and rigidity, etc. Thus, these amino acid changes cantypically be made without altering the biological activity, function, orother desired property of the polypeptide, such as its affinity or itsspecificity for antigen. In general, single amino acid substitutions innonessential regions of a polypeptide do not substantially alterbiological activity. Furthermore, substitutions of amino acids that aresimilar in structure or function are less likely to disrupt thepolypeptides' biological activity.

TABLE 1 Amino Acid Residues and Examples of Conservative Amino AcidSubstitutions Original residue Three letter code and Conservative Singleletter code substitution(s) Alanine (Ala) (A) Gly; Ser Arginine (Arg)(R) Lys; His Asparagine (Asn) (N) Gln; His Aspartic Acid (Asp) (D) Glu;Asn Cysteine (Cys) (C) Ser; Ala Glutamine (Gln) (Q) Asn Glutamic Acid(Glu) (E) Asp; Gln Glycine (Gly) (G) Ala Histidine (His) (H) Asn; GlnIsoleucine (Ile) (I) Leu; Val Leucine (Leu) (L) Ile; Val Lysine (Lys)(K) Arg; His Methionine (Met) (M) Leu; Ile; Tyr Phenylalanine (Phe) (F)Tyr; Met; Leu Proline (Pro) (P) Ala Serine (Ser) (S) Thr Threonine (Thr)(T) Ser Tryptophan (Trp) (W) Tyr; Phe Tyrosine (Tyr) (Y) Trp; Phe Valine(Val) (V) Ile; Leu

The terms “antibody,” “immunoglobulin,” and “Ig” are usedinterchangeably herein in a broad sense and specifically cover, forexample, individual anti-PD-L1 antibodies, such as the monoclonalantibodies described herein, (including agonist, antagonist,neutralizing antibodies, full length or intact monoclonal antibodies,peptide fragments of antibodies that maintain antigen binding activity),anti-unglycosylated PD-L1 antibodies and anti-glycosylated PD-L1antibodies; anti-PD-L1 antibody compositions with polyepitopic ormonoepitopic specificity, polyclonal or monovalent antibodies,multivalent antibodies, multi specific antibodies (e.g., bispecificantibodies so long as they exhibit the desired biological activity),formed from at least two intact antibodies, single chain anti-PD-L1antibodies, and fragments of anti-PD-L1 antibodies, as described below.An antibody can be human, humanized, chimeric and/or affinity matured.An antibody may be from other species, for example, mouse, rat, rabbit,etc. The term “antibody” is intended to include a polypeptide product ofB cells within the immunoglobulin class of polypeptides that is able tobind to a specific molecular antigen. An antibody is typically composedof two identical pairs of polypeptide chains, wherein each pair has oneheavy chain (about 50-70 kDa) and one light chain (about 25 kDa); andwherein the amino-terminal portion of the heavy and light chainsincludes a variable region of about 100 to about 130 or more amino acidsand the carboxy-terminal portion of each chain includes a constantregion (See, Borrebaeck (ed.), 1995, Antibody Engineering, Second Ed.,Oxford University Press.; Kuby, 1997 Immunology, Third Ed., W.H. Freemanand Company, New York). In specific embodiments, the specific molecularantigen bound by an antibody provided herein includes a PD-L1polypeptide, a PD-L1 peptide fragment, or a PD-L1 epitope. The PD-L1polypeptide, PD-L1 peptide fragment, or PD-L1 epitope can beunglycosylated or glycosylated. In a particular embodiment, the PD-L1polypeptide, PD-L1 peptide fragment, or PD-L1 epitope is glycosylated.An antibody or a peptide fragment thereof that binds to a PD-L1 antigencan be identified, for example, by immunoassays, BIAcore, or othertechniques known to those of skill in the art. An antibody or a fragmentthereof binds specifically to a PD-L1 antigen when it binds to a PD-L1antigen with higher affinity than to any cross-reactive antigen asdetermined using experimental techniques, such as radioimmunoassays (MA)and enzyme linked immunosorbent assays (ELISAs). Typically, a specificor selective binding reaction will be at least twice background signalor noise, and more typically more than 5-10 times background signal ornoise. See, e.g., Paul, ed., 1989, Fundamental Immunology SecondEdition, Raven Press, New York at pages 332-336 for a discussionregarding antibody specificity.

Antibodies provided herein include, but are not limited to, syntheticantibodies, monoclonal antibodies, recombinantly produced antibodies,multispecific antibodies (including bi-specific antibodies), humanantibodies, humanized antibodies, camelized antibodies, chimericantibodies, intrabodies, anti-idiotypic (anti-Id) antibodies, andfunctional fragments (e.g., antigen-binding fragments such as PD-L1binding fragments) of any of the above. A binding fragment refers to aportion of an antibody heavy or light chain polypeptide, such as apeptide portion, that retains some or all of the binding activity of theantibody from which the fragment is derived. Non-limiting examples offunctional fragments (e.g., antigen-binding fragments such as PD-L1binding fragments) include single-chain Fvs (scFv) (e.g., includingmonospecific, bispecific, etc.), Fab fragments, F(ab′) fragments, F(ab)₂fragments, F(ab′)₂ fragments, disulfide-linked Fvs (sdFv), Fd fragments,Fv fragments, diabodies, triabodies, tetrabodies and minibodies. Inparticular, antibodies provided herein include immunoglobulin moleculesand immunologically active portions of immunoglobulin molecules, forexample, antigen binding domains or molecules that contain anantigen-binding site that binds to a PD-L1 antigen, in particular, aglycosylated PD-L1 antigen, (e.g., one or more complementaritydetermining regions (CDRs) of an anti-PD-L1 antibody). Description ofsuch antibody fragments can be found in, for example, Harlow and Lane,1989, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory,New York; Myers (ed.), Molec. Biology and Biotechnology: A ComprehensiveDesk Reference, New York: VCH Publisher, Inc.; Huston et al., 1993, CellBiophysics, 22:189-224; Plückthun and Skerra, 1989, Meth. Enzymol.,178:497-515 and in Day, E. D., 1990, Advanced Immunochemistry, SecondEd., Wiley-Liss, Inc., New York, N.Y. The antibodies provided herein canbe of any type (e.g., IgG, IgE, IgM, IgD, IgA and IgY), any class (e.g.,IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2), or any subclass (e.g., IgG2a andIgG2b) of immunoglobulin molecule. Anti-PD-L1 antibodies can beagonistic antibodies or antagonistic antibodies. In certain embodiments,the anti-PD-L1 antibodies are fully human, such as fully humanmonoclonal anti-PD-L1 antibodies. In certain embodiments, the anti-PD-L1antibodies are humanized, such as humanized monoclonal anti-PD-L1antibodies. In certain embodiments, the antibodies provided herein areIgG antibodies, or a class (e.g., human IgG1 or IgG4) or subclassthereof, in particular, IgG1 subclass antibodies.

A four-chain antibody unit is a heterotetrameric glycoprotein composedof two identical light (L) chains and two identical heavy (H) chains. Inthe case of IgGs, the molecular weight of the four-chain (unreduced)antibody unit is generally about 150,000 daltons. Each L chain is linkedto a H chain by one covalent disulfide bond, while the two H chains arelinked to each other by one or more disulfide bonds depending on the Hchain isotype. Each H and L chain also has regularly spaced intrachaindisulfide bridges. At the N-terminus, each H chain has a variable domain(V_(H)) followed by three constant domains (C_(H)) for each of the α andγ chains and four C_(H) domains for μ and ε isotypes. Each L chain hasat the N-terminus, a variable domain (V_(L)) followed by a constantdomain (C_(L)) at its carboxy terminus. The V_(L) domain is aligned withthe V_(H) domain, and the C_(L) domain is aligned with the firstconstant domain of the heavy chain (C_(H1)). Particular amino acidresidues are believed to form an interface between the light chain andheavy chain variable domains. The pairing of a V_(H) and V_(L) togetherforms a single antigen-binding site, although certain V_(H) and V_(L)domains can bind antigen without pairing with a V_(L) or V_(H) domain,respectively. The basic structure of immunoglobulin molecules isunderstood by those having skill in the art. For example, the structureand properties of the different classes of antibodies may be found inTerr, Abba I. et al., 1994, Basic and Clinical Immunology, 8th edition,Appleton & Lange, Norwalk, Conn., page 71 and Chapter 6.

As used herein, the term “antigen” or “target antigen” is apredetermined molecule to which an antibody can selectively bind. Atarget antigen can be a polypeptide, peptide, carbohydrate, nucleicacid, lipid, hapten, or other naturally occurring or synthetic compound.In embodiments, a target antigen is a small molecule. In certainembodiments, the target antigen is a polypeptide or peptide, preferablya glycosylated PD-L1 polypeptide.

As used herein, the term “antigen binding fragment,” “antigen bindingdomain,” “antigen binding region,” and similar terms refer to thatportion of an antibody which includes the amino acid residues thatinteract with an antigen and confer on the antibody as binding agent itsspecificity and affinity for the antigen (e.g., the CDRs of an antibodyare antigen binding regions). The antigen binding region can be derivedfrom any animal species, such as rodents (e.g., rabbit, rat, or hamster)and humans. In specific embodiments, the antigen binding region can beof human origin.

An “isolated” antibody is substantially free of cellular material orother contaminating proteins from the cell or tissue source and/or othercontaminant components from which the antibody is derived, or issubstantially free of chemical precursors or other chemicals whenchemically synthesized. The language “substantially free of cellularmaterial” includes preparations of an antibody in which the antibody isseparated from cellular components of the cells from which it isisolated or recombinantly produced. Thus, an antibody that issubstantially free of cellular material includes preparations of anantibody that have less than about 30%, 25%, 20%, 15%, 10%, 5%, or 1%(by dry weight) of heterologous protein (also referred to herein as a“contaminating protein”). In certain embodiments, when the antibody isrecombinantly produced, it is substantially free of culture medium,e.g., culture medium represents less than about 20%, 15%, 10%, 5%, or 1%of the volume of the protein preparation. In certain embodiments, whenthe antibody is produced by chemical synthesis, it is substantially freeof chemical precursors or other chemicals, for example, it is separatedfrom chemical precursors or other chemicals which are involved in thesynthesis of the protein. Accordingly such preparations of the antibodyhave less than about 30%, 25%, 20%, 15%, 10%, 5%, or 1% (by dry weight)of chemical precursors or compounds other than the antibody of interest.Contaminant components can also include, but are not limited to,materials that would interfere with therapeutic uses for the antibody,and can include enzymes, hormones, and other proteinaceous ornonproteinaceous solutes. In certain embodiments, the antibody ispurified (1) to greater than or equal to 95% by weight of the antibody,as determined by the Lowry method (Lowry et al., 1951, J. Bio. Chem.,193: 265-275), such as 95%, 96%, 97%, 98%, or 99%, by weight, (2) to adegree sufficient to obtain at least 15 residues of N-terminal orinternal amino acid sequence by use of a spinning cup sequenator, or (3)to homogeneity by SDS-PAGE under reducing or nonreducing conditionsusing Coomassie blue or silver stain. Isolated antibody also includesthe antibody in situ within recombinant cells since at least onecomponent of the antibody's natural environment will not be present. Anisolated antibody is typically prepared by at least one purificationstep. In some embodiments, the antibodies provided herein are isolated.

As used herein, the term “binds” or “binding” refers to an interactionbetween molecules including, for example, to form a complex.Illustratively, such interactions embrace non-covalent interactions,including hydrogen bonds, ionic bonds, hydrophobic interactions, and/orvan der Waals interactions. A complex can also include the binding oftwo or more molecules held together by covalent or non-covalent bonds,interactions, or forces. The strength of the total non-covalentinteractions between a single antigen-binding site of an antibody andits epitope on a target (antigen) molecule, such as PD-L1, is theaffinity of the antibody or functional fragment for that epitope. Theratio of association (k_(on)) to dissociation (k_(off)) of an antibodyto a monovalent antigen (k_(on)/k_(off)) is the association constantK_(a), which is a measure of affinity. The value of K varies fordifferent complexes of antibody and antigen and depends on both k_(on)and k_(off). The association constant K_(a) for an antibody providedherein may be determined using any method provided herein or any othermethod known to those skilled in the art. The affinity at one bindingsite does not always reflect the true strength of the interactionbetween an antibody and an antigen. When complex antigens containingmultiple, repeating antigenic determinants come into contact withantibodies containing multiple binding sites, the interaction ofantibody with antigen at one site will increase the probability of aninteraction at a second binding site. The strength of such multipleinteractions between a multivalent antibody and antigen is called theavidity. The avidity of an antibody can be a better measure of itsbinding capacity than is the affinity of its individual binding sites.For example, high avidity can compensate for low affinity as issometimes found for pentameric IgM antibodies, which can have a loweraffinity than IgG, but the high avidity of IgM, resulting from itsmultivalence, enables it to bind antigen effectively.

“Binding affinity” generally refers to the strength of the sum total ofnoncovalent interactions between a single binding site of a molecule(e.g., a binding protein such as an antibody) and its binding partner(e.g., an antigen). Unless indicated otherwise, as used herein, “bindingaffinity” refers to intrinsic binding affinity which reflects a 1:1interaction between members of a binding pair (e.g., antibody andantigen). The affinity of a binding molecule X for its binding partner Ycan generally be represented by the dissociation constant (K_(d)).Affinity can be measured by common methods known in the art, includingthose described herein. Low-affinity antibodies generally bind antigenslowly and tend to dissociate readily, while high-affinity antibodiesgenerally bind antigen faster and tend to remain bound longer toantigen. A variety of methods for measuring binding affinity are knownin the art, any of which may be used for purposes of the presentdisclosure. Specific illustrative embodiments include the following: Inone embodiment, the “K_(d)” or “K_(d) value” is measured by assays knownin the art, for example, by a binding assay. The K_(d) can be measuredin a radiolabeled antigen binding assay (MA), for example, performedwith the Fab portion of an antibody of interest and its antigen (Chen,et al., 1999, J. Mol. Biol., 293:865-881). The K_(d) or K_(d) value mayalso be measured by using surface plasmon resonance (SPR) assays (byBIAcore) using, for example, a BIAcore™-2000 or a BIAcore™-3000(BIAcore, Inc., Piscataway, N.J.), or by biolayer interferometry (BLI)using, for example, the OctetQK384 system (ForteBio, Menlo Park,Calif.), or by quartz crystal microbalance (QCM) technology. An“on-rate” or “rate of association” or “association rate” or “k_(on)” canalso be determined with the same surface plasmon resonance or biolayerinterferometry techniques described above, using, for example, aBIAcore™-2000 or a BIAcore™-3000 (BIAcore, Inc., Piscataway, N.J.), orthe OctetQK384 system (ForteBio, Menlo Park, Calif.).

The terms “anti-PD-L1 antibody,” “an antibody that specifically binds toPD-L1,” or “antibody that is specific for PD-L1,” “antibodies thatspecifically bind to a PD-L1 epitope,” “an antibody that selectivelybinds to PD-L1,” “antibodies that selectively bind to a PD-L1 epitope,”“an antibody that preferentially binds to PD-L1, and analogous terms areused interchangeably herein and refer to antibodies capable of bindingPD-L1, i.e., glycosylated or WT PD-L1, with sufficient affinity andspecificity, particularly compared with non-glycosylated PD-L1 orglycosylation mutants of PD-L1. “Preferential binding” of theanti-glycPD-L1 antibodies as provided herein may be determined ordefined based on the quantification of fluorescence intensity of theantibodies' binding to PD-L1, i.e., glycosylated PD-L1 polypeptide, orPD-L1 WT, or glycosylated PD-L1 expressed on cells versus an appropriatecontrol, such as binding to non-glycosylated or variant PD-L1 (e.g., 4NQPD-L1), or to cells expressing a non-glycosylated or variant form ofPD-L1 (e.g., 4NQ PD-L1), for example, molecularly engineered cells, celllines or tumor cell isolates, such as described herein, e.g., in Example5. Preferential binding of an anti-glycPD-L1 antibody as described to aglycosylated PD-L1 polypeptide or to a glycosylated PD-L1 (PD-L1WT)-expressing cell is indicated by a measured fluorescent bindingintensity (MFI) value, as assessed by cell flow cytometry, of at least2-fold, at least 3-fold, at least 4-fold, at least 5-fold, at least6-fold, at least 7-fold, at least 8-fold, at least 10-fold, at least15-fold, at least 20-fold or greater, as compared with binding of theantibody to a non-glycosylated or mutant glycosylated PD-L1 polypeptideor a non-glycosylated or mutant glycosylated PD-L1-expressing cell,wherein the antibody to be assayed is directly or indirectly detectableby a fluorescent label or marker, such as FITC. In an embodiment, theantibody to be assayed is directly labeled with a fluorescent marker,such as FITC. In embodiments, an anti-glycPD-L1 antibody thatpreferentially or selectively binds glycosylated PD-L1 exhibits an MFIvalue of from 1.5-fold to 25-fold, or from 2-fold to 20-fold, or from3-fold to 15-fold, or from 4-fold to 8-fold, or from 2-fold to 10-fold,or from 2-fold to 5-fold or more greater than the MFI value of the sameantibody for binding a non-glycosylated PD-L1 or a PD-L1 glycosylationvariant as described herein e.g., 4NQ PD-L1, which is not glycosylated.Fold-fluorescence intensity values between and equal to all of theforegoing are intended to be included. In an embodiment, theanti-glycPD-L1 antibodies specifically and preferentially bind to aglycosylated PD-L1 polypeptide, such as a glycosylated PD-L1 antigen,peptide fragment, or epitope (e.g., human glycosylated PD-L1 such as ahuman glycosylated PD-L1 polypeptide, antigen or epitope). An antibodythat specifically binds to PD-L1, (e.g., glycosylated or wild type humanPD-L1) can bind to the extracellular domain (ECD) or a peptide derivedfrom the ECD of PD-L1. An antibody that specifically binds to a PD-L1antigen (e.g., human PD-L1) can be cross-reactive with related antigens(e.g., cynomolgus (cyno) PD-L1). In a preferred embodiment, an antibodythat specifically binds to a PD-L1 antigen does not cross-react withother antigens. An antibody that specifically binds to a PD-L1 antigencan be identified, for example, by immunofluorescence binding assays,immunohistochemistry assay methods, immunoassay methods, Biacore, orother techniques known to those of skill in the art.

In certain other embodiments, an antibody that binds to PD-L1, asdescribed herein, has a dissociation constant (K_(d)) of less than orequal to 20 nM, 19 nM, 18 nM, 17 nM, 16 nM, 15 nM, 14 nM, 13 nM, 12 nM,11 nM, 10 nM, 9 nM, 8 nM, 7 nM, 6 nM, 5 nM, 4 nM, 0.9 nM, 0.8 nM, 0.7nM, 0.6 nM, 0.5 nM, 0.4 nM, 0.3 nM, 0.2 nM, or 0.1 nM, and/or is greaterthan or equal to 0.1 nM. In certain embodiments, an anti-PD-L1 antibodybinds to an epitope of PD-L1 that is conserved among PD-L1 proteins fromdifferent species (e.g., between human and cyno PD-L1). An antibodybinds specifically to a PD-L1 antigen when it binds to a PD-L1 antigenwith higher affinity than to any cross reactive antigen as determinedusing experimental techniques, such as radioimmunoassays (RIA) andenzyme linked immunosorbent assays (ELISAs). Typically a specific orselective reaction will be at least twice background signal or noise andcan be more than 10 times background. See, e.g., Paul, ed., 1989,Fundamental Immunology Second Edition, Raven Press, New York at pages332-336 for a discussion regarding antibody specificity. In suchembodiments, the extent of binding of the antibody to a “non-target”protein will be less than about 10% of the binding of the antibody toits particular target protein, for example, as determined byfluorescence activated cell sorting (FACS) analysis orradioimmunoprecipitation (RIA).

Anti-PD-L1 antibodies include anti-glycosylated PD-L1 antibodies oranti-wild type PD-L1 (PD-L1 WT) antibodies, wherein wild type PD-L1protein is glycosylated, which are specific for glycosylated PD-L1. Inpreferred embodiments, the anti-PD-L1 antibodies are anti-glycPD-L1antibodies that specifically bind glycosylated PD-L1 versusnon-glycosylated PD-L1. In some embodiments, the anti-glycosylated PD-L1antibodies bind to a linear glycosylation motif of PD-L1. In someembodiments, the anti-glycosylated PD-L1 antibodies bind to a peptidesequence that is located near one or more of the glycosylation motifs inthree dimensions. In some embodiments, the anti-glycosylated PD-L1antibodies selectively bind to one or more glycosylation motifs of PD-L1or a PD-L1 peptide having a glycosylation motif of PD-L1 relative tounglycosylated PD-L1. In other embodiments, the anti-glycosylated PD-L1antibodies (anti-glycPD-L1 antibodies) bind to a linear epitopecomprising amino acids of the PD-L1 protein. In some embodiments, theanti-glycosylated PD-L1 antibodies selectively bind to one or moreglycosylation motifs of PD-L1, in which the glycosylation motifscomprise N35, N192 N200, and/or N219 of the PD-L1 polypeptide of SEQ IDNO: 1. In yet other embodiments, the anti-glycPD-L1 antibodies bind to aconformational (nonlinear) epitope comprising amino acids of the PD-L1protein. In some embodiments, an anti-glycPD-L1 antibody, or a bindingportion thereof, binds to glycosylated PD-L1 with a K_(d) less than atleast 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%of the Kd exhibited relative to unglycosylated PD-L1. In certainembodiments, an anti-glycPD-L1 antibody, or a binding portion thereof,binds to glycosylated PD-L1 with a K_(d) less than 50% of the Kdexhibited relative to unglycosylated PD-L1. In some embodiments, ananti-glycPD-L1 antibody, or a binding portion thereof, binds toglycosylated PD-L1 with a K_(d) that is less than 1%, 2%, 3%, 4%, 5%,6%, 7%, 8%, 9%, 10%, 15%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 70%, 75%,80%, 85%, or 90% of the K_(d) exhibited relative to unglycosylatedPD-L1. In further aspects, an anti-glycPD-L1 antibody, or a bindingportion thereof, binds to glycosylated PD-L1 with a K_(d) at least 5-10times less than the K_(d) exhibited relative to unglycosylated PD-L1. Inan embodiment, an anti-glycPD-L1 antibody, or a binding portion thereof,binds to glycosylated PD-L1 with a K_(d) at least 10 times less than theK_(d) exhibited relative to unglycosylated PD-L1. In certainembodiments, the antibody binds to glycosylated PD-L1 with a K_(d) thatis no more than 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, or 20% ofthe K_(d) exhibited by binding to unglycosylated PD-L1.

In an embodiment, in a cell flow cytometry binding assay as described inExample 5, the antibody exhibits binding as expressed as MFI to cellsexpressing WT PD-L1 that is at least or is 1.5 times, 2 times, 3, times,4 times, 5 times, 6 times, 7 times, 8 times, 9 times or 10 times greaterthan the MFI for binding to cells expressing unglycosylated PD-L1, andin certain embodiments, is no more than 10 times, 20 times 50 times or100 times greater than the MFI for binding to cells expressingunglycosylated PD-L1. In an embodiment, an anti-glycPD-L1 antibody, or abinding portion thereof, binds to glycosylated PD-L1 with a nanomolaraffinity, such as an affinity of from 5-20 nM or from 10-20 nM,inclusive of the lower and upper values.

As used herein in reference to an antibody, the term “heavy (H) chain”refers to a polypeptide chain of about 50-70 kDa, wherein theamino-terminal portion includes a variable (V) region (also called Vdomain) of about 115 to 130 or more amino acids and a carboxy-terminalportion that includes a constant (C) region. The constant region (orconstant domain) can be one of five distinct types, (e.g., isotypes)referred to as alpha (α), delta (δ), epsilon (ε), gamma (γ) and mu (μ),based on the amino acid sequence of the heavy chain constant region. Thedistinct heavy chains differ in size: α, δ and γ contain approximately450 amino acids, while μ and ε contain approximately 550 amino acids.When combined with a light chain, these distinct types of heavy chainsgive rise to five well known classes (e.g., isotypes) of antibodies,namely, IgA, IgD, IgE, IgG and IgM, respectively, including foursubclasses of IgG, namely IgG1, IgG2, IgG3 and IgG4. An antibody heavychain can be a human antibody heavy chain.

As used herein in reference to an antibody, the term “light (L) chain”refers to a polypeptide chain of about 25 kDa, wherein theamino-terminal portion includes a variable domain of about 100 to about110 or more amino acids and a carboxy-terminal portion that includes aconstant region. The approximate length of a light chain (both the V andC domains) is 211 to 217 amino acids. There are two distinct types oflight chains, referred to as kappa (κ) and lambda (λ), based on theamino acid sequence of the constant domains. Light chain amino acidsequences are well known in the art. An antibody light chain can be ahuman antibody light chain.

As used herein, the term “variable (V) region” or “variable (V) domain”refers to a portion of the light (L) or heavy (H) chains of an antibodypolypeptide that is generally located at the amino-terminus of the L orH chain. The H chain V domain has a length of about 115 to 130 aminoacids, while the L chain V domain is about 100 to 110 amino acids inlength. The H and L chain V domains are used in the binding andspecificity of each particular antibody for its particular antigen. TheV domain of the H chain can be referred to as “V_(H).” The V region ofthe L chain can be referred to as “V_(L).” The term “variable” refers tothe fact that certain segments of the V domains differ extensively insequence among different antibodies. While the V domain mediates antigenbinding and defines specificity of a particular antibody for itsparticular antigen, the variability is not evenly distributed across the110-amino acid span of antibody V domains. Instead, the V domainsconsist of less variable (e.g., relatively invariant) stretches calledframework regions (FRs) of about 5-30 amino acids separated by shorterregions of greater variability (e.g., extreme variability) called“hypervariable regions” or “complementarity determining regions” (CDRs)that are each about 9-12 amino acids long. The V domains of antibody Hand L chains each comprise four FRs, largely adopting a β sheetconfiguration, connected by three hypervariable regions, called, whichform loops connecting, and in some cases forming part of, the β sheetstructure. The hypervariable regions in each chain are held together inclose proximity by the FRs and, with the hypervariable regions from theother chain, contribute to the formation of the antigen-binding site ofantibodies (see, e.g., Kabat et al., 1991, Sequences of Proteins ofImmunological Interest, 5th Ed. Public Health Service, NationalInstitutes of Health, Bethesda, Md.). The C domains are not involveddirectly in binding an antibody to an antigen, but exhibit variouseffector functions, such as antibody dependent cellular cytotoxicity(ADCC) and complement dependent cytotoxicity (CDC). The V domains differextensively in sequence among different antibody classes or types. Thevariability in sequence is concentrated in the CDRs, which are primarilyresponsible for the interaction of the antibody with antigen. Inspecific embodiments, the variable domain of an antibody is a human orhumanized variable domain.

As used herein, the terms “complementarity determining region,” “CDR,”“hypervariable region,” “HVR,” and “HV” are used interchangeably. A“CDR” refers to one of three hypervariable regions (H1, H2 or H3) withinthe non-framework region of the antibody V_(H) β-sheet framework, or toone of three hypervariable regions (L1, L2 or L3) within thenon-framework region of the antibody V_(L) β-sheet framework. The term,when used herein, refers to the regions of an antibody V domain that arehypervariable in sequence and/or form structurally defined loops.Generally, antibodies comprise six hypervariable regions: three (H1, H2,H3) in the V_(H) domain and three (L1, L2, L3) in the V_(L) domain.Accordingly, CDRs are typically highly variable sequences interspersedwithin the framework region sequences of the V domain. “Framework” or“FR” residues are those variable region residues flanking the CDRs. FRresidues are present, for example, in chimeric, humanized, human, domainantibodies, diabodies, linear antibodies, and bispecific antibodies.

A number of hypervariable region delineations are in use and areencompassed herein. CDR regions are well known to those skilled in theart and have been defined by, for example, Kabat as the regions of mosthypervariability within the antibody V domains (Kabat et al., 1977, J.Biol. Chem., 252:6609-6616; Kabat, 1978, Adv. Prot. Chem., 32:1-75). TheKabat CDRs are based on sequence variability and are the most commonlyused (see, e.g., Kabat et al., 1991, Sequences of Proteins ofImmunological Interest, 5th Ed. Public Health Service, NationalInstitutes of Health, Bethesda, Md.). CDR region sequences also havebeen defined structurally by Chothia as those residues that are not partof the conserved β-sheet framework, and thus are able to adopt differentconformations (Chothia et al., 1987, J. Mol. Biol., 196:901-917).Chothia refers instead to the location of the structural loops. The endof the Chothia CDR-H1 loop when numbered using the Kabat numberingconvention varies between H32 and H34 depending on the length of theloop (this is because the Kabat numbering scheme places the insertionsat H35A and H35B; if neither 35A nor 35B is present, the loop ends at32; if only 35A is present, the loop ends at 33; if both 35A and 35B arepresent, the loop ends at 34). Both numbering systems and terminologiesare well recognized in the art.

Recently, a universal numbering system has been developed and widelyadopted, ImMunoGeneTics (IMGT) Information System® (Lafranc et al.,2003, Dev. Comp. Immunol., 27(1):55-77). IMGT is an integratedinformation system specializing in immunoglobulins (Ig), T cellreceptors (TR) and the major histocompatibility complex (MHC) of humanand other vertebrates. Herein, the CDRs are referred to in terms of boththe amino acid sequence and the location within the light or heavychain. As the “location” of the CDRs within the structure of theimmunoglobulin V domain is conserved between species and present instructures called loops, by using numbering systems that align variabledomain sequences according to structural features, CDR and frameworkresidues and are readily identified. This information can be used ingrafting and in the replacement of CDR residues from immunoglobulins ofone species into an acceptor framework from, typically, a humanantibody. An additional numbering system (AHon) has been developed byHonegger et al., 2001, J. Mol. Biol., 309: 657-670. Correspondencebetween the numbering system, including, for example, the Kabatnumbering and the IMGT unique numbering system, is well known to oneskilled in the art (see, e.g., Kabat, Id; Chothia et al., Id.; Martin,2010, Antibody Engineering, Vol. 2, Chapter 3, Springer Verlag; andLefranc et al., 1999, Nuc. Acids Res., 27:209-212).

CDR region sequences have also been defined by AbM, Contact and IMGT.The AbM hypervariable regions represent a compromise between the KabatCDRs and Chothia structural loops, and are used by Oxford Molecular'sAbM antibody modeling software (see, e.g., Martin, 2010, AntibodyEngineering, Vol. 2, Chapter 3, Springer Verlag). The “contact”hypervariable regions are based on an analysis of the available complexcrystal structures. The residues from each of these hypervariableregions or CDRs are noted below.

Exemplary delineations of CDR region sequences are illustrated in Table2 below. The positions of CDRs within a canonical antibody variableregion have been determined by comparison of numerous structures(Al-Lazikani et al., 1997, J. Mol. Biol., 273:927-948); Morea et al.,2000, Methods, 20:267-279). Because the number of residues within ahypervariable region varies in different antibodies, additional residuesrelative to the canonical positions are conventionally numbered with a,b, c and so forth next to the residue number in the canonical variableregion numbering scheme (Al-Lazikani et al., Id). Such nomenclature issimilarly well known to those skilled in the art.

TABLE 2 Exemplary Delineations of CDR Region Sequences IMGT Kabat AbMChothia Contact V_(H) CDR1 27-38 31-35 26-35 26-32 30-35 V_(H) CDR256-65 50-65 50-58 53-55 47-58 V_(H) CDR3 105-117  95-102  95-102  96-101 93-101 V_(L) CDR1 27-38 24-34 24-34 26-32 30-36 V_(L) CDR2 56-65 50-5650-56 50-52 46-55 V_(L) CDR3 105-117 89-97 89-97 91-96 89-96

An “affinity matured” antibody is one with one or more alterations(e.g., amino acid sequence variations, including changes, additionsand/or deletions) in one or more HVRs thereof that result in animprovement in the affinity of the antibody for antigen, compared to aparent antibody which does not possess those alteration(s). In certainembodiments, affinity matured antibodies will have nanomolar or evenpicomolar affinities for the target antigen, such as the glycosylatedPD-L1. Affinity matured antibodies are produced by procedures known inthe art. For reviews, see Hudson and Souriau, 2003, Nature Medicine,9:129-134; Hoogenboom, 2005, Nature Biotechnol., 23:1105-1116; Quirozand Sinclair, 2010, Revista Ingeneria Biomedia, 4:39-51.

A “chimeric” antibody is one in which a portion of the H and/or L chain,e.g., the V domain, is identical with or homologous to a correspondingamino acid sequence in an antibody derived from a particular species orbelonging to a particular antibody class or subclass, while theremainder of the chain(s), e.g., the C domain, is identical with orhomologous to corresponding sequences in antibodies derived from anotherspecies or belonging to another antibody class or subclass, as well as afragment of such an antibody, so long as it exhibits the desiredbiological activity (see, e.g., U.S. Pat. No. 4,816,567; and Morrison etal., 1984, Proc. Natl. Acad. Sci. USA, 81:6851-6855).

A “humanized” nonhuman (e.g., murine) antibody is a chimeric form of anantibody that refers to a human immunoglobulin sequence (e.g., recipientantibody) in which the native CDR residues are replaced by residues fromthe corresponding CDRs of a nonhuman species (e.g., donor antibody) suchas mouse, rat, rabbit or nonhuman primate having the desiredspecificity, affinity, and capacity for antigen binding and interaction.In some instances, one or more FR region residues of the humanimmunoglobulin may also be replaced by corresponding nonhuman residues.In addition, humanized antibodies can comprise residues that are notfound in the recipient antibody or in the donor antibody. Thesemodifications are made to further refine the humanized antibody'sperformance. A humanized antibody H or L chain may comprisesubstantially all of at least one or more variable regions, in which allor substantially all of the CDRs correspond to those of a nonhumanimmunoglobulin and all or substantially all of the FRs are those of ahuman immunoglobulin sequence. In certain embodiments, the humanizedantibody will comprise at least a portion of an immunoglobulin constantregion (Fc), typically that of a human immunoglobulin. While known tothose skilled in the art, further details may be found, if desired, in,e.g., Jones et al., 1986, Nature, 321:522-525; Riechmann et al., 1988,Nature, 332:323-329; and Presta, 1992, Curr. Op. Struct. Biol.,2:593-596; Carter et al., 1992, Proc. Natl. Acad. Sci. USA,89:4285-4289; and U.S. Pat. No. 6,800,738 (issued Oct. 5, 2004), U.S.Pat. No. 6,719,971 (issued Sep. 27, 2005), U.S. Pat. No. 6,639,055(issued Oct. 28, 2003), U.S. Pat. No. 6,407,213 (issued Jun. 18, 2002),and U.S. Pat. No. 6,054,297 (issued Apr. 25, 2000).

The terms “human antibody” and “fully human antibody” are usedinterchangeably herein and refer to an antibody that possesses an aminoacid sequence which corresponds to that of an antibody produced by ahuman and/or has been made using any of the techniques for making humanantibodies as practiced by those skilled in the art. This definition ofa human antibody specifically excludes a humanized antibody comprisingnon-human antigen-binding residues. Human antibodies can be producedusing various techniques known in the art, including phage-displaylibraries (Hoogenboom et al., 1991, J. Mol. Biol., 227:381; Marks etal., 1991, J. Mol. Biol., 222:581 and yeast display libraries (Chao etal., 2006, Nature Protocols, 1:755-768). Also available for thepreparation of human monoclonal antibodies are methods described in Coleet al., 1985 Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, p.77; Boerner et al., 1991, J. Immunol., 147(1):86-95. See also van Dijket al., 2001, Curr. Opin. Pharmacol., 5: 368-74. Human antibodies can beprepared by administering an antigen to a transgenic animal whoseendogenous Ig loci have been disabled, e.g., a mouse, and that has beengenetically modified to harbor human immunoglobulin genes which encodehuman antibodies, such that human antibodies are generated in responseto antigenic challenge (see, e.g., Jakobovits, A., 1995, Curr. Opin.Biotechnol. 6(5):561-566; Bruggemann et al, 1997 Curr. Opin.Biotechnol., 8(4):455-8; and U.S. Pat. Nos. 6,075,181 and 6,150,584regarding XENOMOUSE™ technology). See also, for example, Li et al.,2006, Proc. Natl. Acad. Sci. USA, 103:3557-3562 regarding humanantibodies generated via a human B-cell hybridoma technology. Inspecific embodiments, human antibodies comprise a variable region andconstant region of human origin. “Fully human” anti-PD-L1 antibodies, incertain embodiments, can also encompass antibodies which bind PD-L1polypeptides and are encoded by nucleic acid sequences which arenaturally occurring somatic variants of human germline immunoglobulinnucleic acid sequence. In a specific embodiment, the anti-PD-L1antibodies provided herein are fully human antibodies. The term “fullyhuman antibody” includes antibodies having variable and constant regionscorresponding to human germline immunoglobulin sequences as described byKabat et al. (See Kabat et al., 1991, Sequences of Proteins ofImmunological Interest, Fifth Edition, U.S. Department of Health andHuman Services, NIH Publication No. 91-3242). The phrase “recombinanthuman antibody” includes human antibodies that are prepared, expressed,created, or isolated by recombinant means, such as antibodies expressedusing a recombinant expression vector transfected into a host cell;antibodies isolated from a recombinant, combinatorial human antibodylibrary; antibodies isolated from an animal (e.g., a mouse or cow) thatis transgenic and/or transchromosomal for human immunoglobulin genes(see e.g., Taylor, L. D. et al., 1992, Nucl. Acids Res. 20:6287-6295);or antibodies prepared, expressed, created or isolated by any othermeans that involves splicing of human immunoglobulin gene sequences toother DNA sequences. Such recombinant human antibodies can have variableand constant regions derived from human germline immunoglobulinsequences (See Kabat et al., 1991, Sequences of Proteins ofImmunological Interest, Fifth Edition, U.S. Department of Health andHuman Services, NIH Publication No. 91-3242). In certain embodiments,however, such recombinant human antibodies are subjected to in vitromutagenesis (or, when an animal transgenic for human Ig sequences isused, in vivo somatic mutagenesis) and thus the amino acid sequences ofthe V_(H) and V_(L) regions of the recombinant antibodies are sequencesthat, while derived from and related to human germline V_(H) and V_(L)sequences, may not naturally exist within the human antibody germlinerepertoire in vivo.

As used herein, the term “epitope” is the site(s) or region(s) on thesurface of an antigen molecule to which a single antibody moleculebinds, such as a localized region on the surface of an antigen, e.g., aPD-L1 polypeptide or a glycosylated PD-L1 polypeptide that is capable ofbeing bound by one or more antigen binding regions of an anti-PD-L1 oranti-glycPD-L1 antibody. An epitope can be immunogenic and capable ofeliciting an immune response in an animal. Epitopes need not necessarilybe immunogenic. Epitopes often consist of chemically active surfacegroupings of molecules such as amino acids or sugar side chains and havespecific three dimensional structural characteristics as well asspecific charge characteristics. An epitope can be a linear epitope anda conformational epitope. A region of a polypeptide contributing to anepitope can be contiguous amino acids of the polypeptide, forming alinear epitope, or the epitope can be formed from two or morenon-contiguous amino acids or regions of the polypeptide, typicallycalled a conformational epitope. The epitope may or may not be athree-dimensional surface feature of the antigen. In certainembodiments, a PD-L1 epitope is a three-dimensional surface feature of aPD-L1 polypeptide. In other embodiments, a PD-L1 epitope is linearfeature of a PD-L1 polypeptide. In some embodiments, the PD-L1 epitopeis unglycosylated PD-L1 polypeptide. In some embodiments, the PD-L1epitope is glycosylated at one or more sites. Generally an antigen hasseveral or many different epitopes and can react with many differentantibodies. In a particular embodiment, an anti-glycPD-L1 antibody, asdescribed, binds an epitope of PD-L1, especially glycosylated PD-L1,that is a conformational epitope.

An antibody binds “an epitope” or “essentially the same epitope” or “thesame epitope” as a reference antibody, when the two antibodies recognizeidentical, overlapping, or adjacent epitopes in a three-dimensionalspace. The most widely used and rapid methods for determining whethertwo antibodies bind to identical, overlapping, or adjacent epitopes in athree-dimensional space are competition assays, which can be configuredin a number of different formats, for example, using either labeledantigen or labeled antibody. In some assays, the antigen is immobilizedon a 96-well plate, or expressed on a cell surface, and the ability ofunlabeled antibodies to block the binding of labeled antibodies toantigen is measured using a detectable signal, e.g., radioactive,fluorescent or enzyme labels.

The term “compete” when used in the context of anti-PD-L1 antibodiesthat compete for the same epitope or binding site on a PD-L1 targetprotein or peptide thereof means competition as determined by an assayin which the antibody under study, or binding fragment thereof,prevents, blocks, or inhibits the specific binding of a referencemolecule (e.g., a reference ligand, or reference antigen bindingprotein, such as a reference antibody) to a common antigen (e.g., PD-L1or a fragment thereof). Numerous types of competitive binding assays canbe used to determine if a test antibody competes with a referenceantibody for binding to PD-L1 (e.g., human PD-L1 or human glycosylatedPD-L1). Examples of assays that can be employed include solid phasedirect or indirect radioimmunoassay (RIA); solid phase direct orindirect enzyme immunoassay (EIA); sandwich competition assay (see,e.g., Stahli et al., 1983, Methods in Enzymology 9:242-253); solid phasedirect biotin-avidin EIA (see, e.g., Kirkland et al., 1986, J. Immunol.137:3614-3619); solid phase direct labeled assay; solid phase directlabeled sandwich assay (see, e.g., Harlow and Lane, 1988, Antibodies, ALaboratory Manual, Cold Spring Harbor Press); solid phase direct labelRIA using labeled iodine (1¹²⁵ label) (see, e.g., Morel et al., 1988,Molec. Immunol. 25:7-15); solid phase direct biotin-avidin EIA (see,e.g., Cheung, et al., 1990, Virology 176:546-552); and direct labeledRIA (Moldenhauer et al., 1990, Scand. J. Immunol. 32:77-82). Typically,such an assay involves the use of a purified antigen (e.g., PD-L1 suchas human PD-L1 or glycosylated PD-L1) bound to a solid surface, or cellsbearing either of an unlabeled test antigen binding protein (e.g., testanti-PD-L1 antibody) or a labeled reference antigen binding protein(e.g., reference anti-PD-L1 antibody). Competitive inhibition can bemeasured by determining the amount of label bound to the solid surfaceor cells in the presence of a known amount of the test antigen bindingprotein. Usually the test antigen binding protein is present in excess.Antibodies identified by competition assay (competing antibodies)include antibodies binding to the same epitope as the reference antibodyand/or antibodies binding to an adjacent epitope sufficiently proximalto the epitope bound by the reference antibody causing steric hindranceto occur. Additional details regarding methods for determiningcompetitive binding are described herein. Usually, when a competingantibody protein is present in excess, it will inhibit specific bindingof a reference antibody to a common antigen by at least 15%, or at least23%, for example, without limitation, 40%, 45%, 50%, 55%, 60%, 65%, 70%or 75% or greater, as well as percent amounts between the amountsstated. In some instance, binding is inhibited by at least 80%, 85%,90%, 95%, 96% or 97%, 98%, 99% or more.

As used herein, the term “blocking” antibody or an “antagonist” antibodyrefers to an antibody that prevents, inhibits, blocks, or reducesbiological or functional activity of the antigen to which it binds.Blocking antibodies or antagonist antibodies can substantially orcompletely prevent, inhibit, block, or reduce the biological activity orfunction of the antigen. For example, a blocking anti-PD-L1 antibody canprevent, inhibit, block, or reduce the binding interaction between PD-L1and PD-1, thus preventing, blocking, inhibiting, or reducing theimmunosuppressive functions associated with the PD-1/PD-L1 interaction.The terms block, inhibit, and neutralize are used interchangeably hereinand refer to the ability of the anti-glycPD-L1 antibodies to prevent orotherwise disrupt or reduce the PD-L1/PD-1 interaction.

As used herein, the term “polypeptide” or “peptide” refers to a polymerof amino acids of three or more amino acids in a serial array, linkedthrough peptide bonds. “Polypeptides” can be proteins, proteinfragments, protein analogs, oligopeptides and the like. The amino acidsthat comprise the polypeptide may be naturally derived or synthetic. Thepolypeptide may be purified from a biological sample. For example, aPD-L1 polypeptide or peptide may be composed of at least 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25contiguous amino acids of human PD-L1 or glycosylated PD-L1. In someembodiments, the polypeptide has at least 25, 30, 35, 40, 45, 50, 55,60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135,140, 145, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260,270, 280, or 285 contiguous amino acids of human PD-L1 or glycosylatedPD-L1. In certain embodiments, the PD-L1 polypeptide comprises at least5 contiguous amino acid residues, at least 10 contiguous amino acidresidues, at least 15 contiguous amino acid residues, at least 20contiguous amino acid residues, at least 25 contiguous amino acidresidues, at least 40 contiguous amino acid residues, at least 50contiguous amino acid residues, at least 60 contiguous amino residues,at least 70 contiguous amino acid residues, at least 80 contiguous aminoacid residues, at least 90 contiguous amino acid residues, at leastcontiguous 100 amino acid residues, at least 125 contiguous amino acidresidues, at least 150 contiguous amino acid residues, at least 175contiguous amino acid residues, at least 200 contiguous amino acidresidues, at least 250 contiguous amino acid residues of the amino acidsequence of a PD-L1 polypeptide or a glycosylated PD-L1 polypeptide.

As used herein, the term “analog” refers to a polypeptide that possessesa similar or identical function as a reference polypeptide but does notnecessarily comprise a similar or identical amino acid sequence of thereference polypeptide, or possess a similar or identical structure ofthe reference polypeptide. The reference polypeptide may be a PD-L1polypeptide, a fragment of a PD-L1 polypeptide, an anti-PD-L1 antibody,or an anti-glycPD-L1 antibody. A polypeptide that has a similar aminoacid sequence with a reference polypeptide refers to a polypeptidehaving an amino acid sequence that is at least 30%, at least 35%, atleast 40%, at least 45%, at least 50%, at least 55%, at least 60%, atleast 65%, at least 70%, at least 75%, at least 80%, at least 85%, atleast 90%, at least 95%, or at least 99% identical to the amino acidsequence of the reference polypeptide, which can be a PD-L1 polypeptideor an anti-glycPD-L1 antibody as described herein. A polypeptide withsimilar structure to a reference polypeptide refers to a polypeptidethat has a secondary, tertiary, or quaternary structure similar to thatof the reference polypeptide, which can be a PD-L1 polypeptide or ananti-glycPD-L1 antibody described herein. The structure of a polypeptidecan determined by methods known to those skilled in the art, including,but not limited to, X-ray crystallography, nuclear magnetic resonance(NMR), and crystallographic electron microscopy.

As used herein, the term “variant” when used in relation to a PD-L1polypeptide or to an anti-PD-L1 antibody refers to a polypeptide or ananti-PD-L1 antibody having one or more (such as, for example, about 1 toabout 25, about 1 to about 20, about 1 to about 15, about 1 to about 10,or about 1 to about 5 amino acid sequence substitutions, deletions,and/or additions as compared to a native or unmodified PD-L1 sequence oranti-PD-L1 antibody sequence. For example, a PD-L1 variant can resultfrom one or more (such as, for example, about 1 to about 25, about 1 toabout 20, about 1 to about 15, about 1 to about 10, or about 1 to about5) changes to an amino acid sequence of a native PD-L1. Also by way ofexample, a variant of an anti-PD-L1 antibody can result from one or more(such as, for example, about 1 to about 25, about 1 to about 20, about 1to about 15, about 1 to about 10, or about 1 to about 5 changes to anamino acid sequence of a native or previously unmodified anti-PD-L1antibody. Variants can be naturally occurring, such as allelic or splicevariants, or can be artificially constructed. Polypeptide variants canbe prepared from the corresponding nucleic acid molecules encoding thevariants.

The term “identity” refers to a relationship between the sequences oftwo or more polypeptide molecules or two or more nucleic acid molecules,as determined by aligning and comparing the sequences. “Percentidentity” means the percent of identical residues between the aminoacids or nucleotides in the compared molecules and is calculated basedon the size of the smallest of the molecules being compared. For thesecalculations, gaps in alignments (if any) must be addressed by aparticular mathematical model or computer program (e.g., an“algorithm”). Methods that may be used to calculate the identity of thealigned nucleic acids or polypeptides include those described in Lesk,A. M., ed., 1988, Computational Molecular Biology, New York: OxfordUniversity Press; Smith, D. W., ed., 1993, Biocomputing Informatics andGenome Projects, New York: Academic Press; Griffin, A. M., et al., 1994,Computer Analysis of Sequence Data, Part I, New Jersey: Humana Press;von Heinje, G., 1987, Sequence Analysis in Molecular Biology, New York:Academic Press; Gribskov, M. et al., 1991, Sequence Analysis Primer, NewYork: M. Stockton Press; and Carillo et al., 1988, Applied Math.,48:1073.

In calculating percent identity, the sequences being compared can bealigned in a way that gives the largest match between the sequences. Anexample of a computer program that can be used to determine percentidentity is the GCG program package, which includes GAP (Devereux etal., 1984, Nucl. Acid Res., 12:387; Genetics Computer Group, Universityof Wisconsin, Madison, Wis.), which is a computer algorithm used toalign the two polypeptides or polynucleotides to determine their percentsequence identity. The sequences can be aligned for optimal matching oftheir respective amino acid or nucleotide sequences (the “matched span”as determined by the algorithm). A gap opening penalty (which iscalculated as 3 times the average diagonal, wherein the “averagediagonal” is the average of the diagonal of the comparison matrix beingused, and the “diagonal” is the score or number assigned to each perfectamino acid match by the particular comparison matrix; and a gapextension penalty (which is usually 1/10 times the gap opening penalty),as well as a comparison matrix such as PAM 250 or BLOSUM 62, are used inconjunction with the algorithm. In certain embodiments, a standardcomparison matrix (see, Dayhoff et al., 1978, Atlas of Protein Sequenceand Structure 5:345-352 for the PAM 250 comparison matrix; Henikoff etal., 1992, Proc. Natl. Acad. Sci. USA 89:10915-10919 for the BLOSUM 62comparison matrix) is also used by the algorithm. Exemplary parametersfor determining percent identity for polypeptides or nucleotidesequences using the GAP program include the following: (i) Algorithm:Needleman et al., 1970, J. Mol. Biol., 48:443-453; (ii) Comparisonmatrix: BLOSUM 62 from Henikoff et al., Id.; (iii) Gap Penalty: 12 (butwith no penalty for end gaps); (iv) Gap Length Penalty: 4; and (v)Threshold of Similarity: 0.

Certain alignment schemes for aligning two amino acid sequences canresult in matching only a short region of the two sequences, and thissmall aligned region can have very high sequence identity even thoughthere is no significant relationship between the two full-lengthsequences. Accordingly, the selected alignment method (e.g., the GAPprogram) can be adjusted if so desired to result in an alignment thatspans a representative number of amino acids, for example, at least 50contiguous amino acids, of the target polypeptide.

Percent (%) amino acid sequence identity with respect to a referencepolypeptide sequence is defined as the percentage of amino acid residuesin a candidate sequence that is identical with the amino acid residuesin the reference polypeptide sequence, after aligning the sequences andintroducing gaps, if necessary, to achieve the maximum percent sequenceidentity, and not considering any conservative substitutions as part ofthe sequence identity. Alignment for purposes of determining percentamino acid sequence identity can be achieved in various ways that arewithin the skill of the practitioner in the art, for instance, usingpublicly available computer software such as BLAST, BLAST-2, ALIGN orMegalign (DNASTAR) software. Those skilled in the art can determineappropriate parameters for aligning sequences, including any algorithmsneeded to achieve maximal alignment over the full length of thesequences being compared.

As used herein, the term “derivative” refers to a polypeptide thatcomprises an amino acid sequence of a reference polypeptide that hasbeen altered by the introduction of amino acid residue substitutions,deletions or additions. The reference polypeptide can be a PD-L1polypeptide or an anti-PD-L1 antibody. The term “derivative” as usedherein also refers to a PD-L1 polypeptide or an anti-PD-L1 antibody thathas been chemically modified, e.g., by the covalent attachment of anytype of molecule to the polypeptide. For example, a PD-L1 polypeptide oran anti-PD-L1 antibody can be chemically modified, e.g., byglycosylation, acetylation, pegylation, phosphorylation, amidation,derivatization by known protecting/blocking groups, proteolyticcleavage, linkage to a cellular ligand, linkage to a peptide or proteintag molecule, or other protein, etc. The derivatives are modified in amanner that is different from the naturally occurring or startingpeptide or polypeptides, either in the type or location of the moleculesattached. Derivatives may further include deletion of one or morechemical groups which are naturally present on the peptide orpolypeptide. A derivative of a PD-L1 polypeptide or an anti-PD-L1antibody may be chemically modified by chemical modifications usingtechniques known to those of skill in the art, including, but notlimited to, specific chemical cleavage, acetylation, formulation,metabolic synthesis by tunicamycin, etc. Further, a derivative of aPD-L1 polypeptide or an anti-PD-L1 antibody can contain one or morenon-classical amino acids. A polypeptide derivative possesses a similaror identical function as the reference polypeptide, which can be a PD-L1polypeptide or an anti-PD-L1 antibody described herein, especially ananti-glycPD-L1 monoclonal antibody.

The term “fusion protein” as used herein refers to a polypeptide thatincludes amino acid sequences of at least two heterologous polypeptides.The term “fusion” when used in relation to a PD-L1 polypeptide or to ananti-PD-L1 antibody refers to the joining, fusing, or coupling of aPD-L1 polypeptide or an anti-PD-L1 antibody, variant and/or derivativethereof, with a heterologous peptide or polypeptide. In certainembodiments, the fusion protein retains the biological activity of thePD-L1 polypeptide or the anti-PD-L1 antibody. In certain embodiments,the fusion protein includes a PD-L1 antibody V_(H) region, V_(L) region,V_(H) CDR (one, two or three V_(H) CDRs), and/or V_(L) CDR (one, two orthree V_(L) CDRs) coupled, fused, or joined to a heterologous peptide orpolypeptide, wherein the fusion protein binds to an epitope on a PD-L1protein or peptide. Fusion proteins may be prepared via chemicalcoupling reactions as practiced in the art, or via molecular recombinanttechnology.

As used herein, the term “composition” refers to a product containingspecified component ingredients (e.g., a polypeptide or an antibodyprovided herein) in, optionally, specified or effective amounts, as wellas any desired product which results, directly or indirectly, from thecombination or interaction of the specific component ingredients in,optionally, the specified or effective amounts.

As used herein, the term “carrier” includes pharmaceutically acceptablecarriers, excipients, diluents, vehicles, or stabilizers that arenontoxic to the cell or mammal being exposed thereto at the dosages andconcentrations employed. Often, the physiologically acceptable carrieris an aqueous pH buffered solution. Examples of physiologicallyacceptable carriers include buffers such as phosphate, citrate,succinate, and other organic acids; antioxidants including ascorbicacid; low molecular weight (e.g., less than about 10 amino acidresidues) polypeptides; proteins, such as serum albumin, gelatin, orimmunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone;amino acids such as glycine, glutamine, asparagine, histidine, arginineor lysine; monosaccharides, disaccharides, and other carbohydratesincluding glucose, mannose, sucrose, or dextrins; chelating agents suchas EDTA; sugar alcohols such as mannitol or sorbitol; salt-formingcounterions such as sodium; and/or nonionic surfactants such as TWEEN™,polyethylene glycol (PEG), and PLURONICS™. The term “carrier” can alsorefer to a diluent, adjuvant (e.g., Freund's adjuvant, complete orincomplete), excipient, or vehicle with which the therapeutic isadministered. Such carriers, including pharmaceutical carriers, can besterile liquids, such as water and oils, including those of petroleum,animal, vegetable or synthetic origin, such as peanut oil, soybean oil,mineral oil, sesame oil and the like. Water is an exemplary carrier whena composition (e.g., a pharmaceutical composition) is administeredintravenously. Saline solutions and aqueous dextrose and glycerolsolutions can also be employed as liquid carriers, particularly forinjectable solutions. Suitable excipients (e.g., pharmaceuticalexcipients) include, without limitation, starch, glucose, lactose,sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate,glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol,propylene, glycol, water, ethanol and the like. The composition, ifdesired, can also contain minor amounts of wetting or emulsifyingagents, or pH buffering agents. Compositions can take the form ofsolutions, suspensions, emulsion, tablets, pills, capsules, powders,sustained-release formulations and the like. Oral compositions,including formulations, can include standard carriers such aspharmaceutical grades of mannitol, lactose, starch, magnesium stearate,sodium saccharine, cellulose, magnesium carbonate, etc. Examples ofsuitable pharmaceutical carriers are described in RemingtonPharmaceutical Sciences, (1990) Mack Publishing Co., Easton, Pa.Compositions, including pharmaceutical compounds, can contain atherapeutically effective amount of an anti-PD-L1 antibody, such as ananti-glycPD-L1 antibody, for example, in isolated or purified form,together with a suitable amount of carrier so as to provide the form forproper administration to the subject (e.g., patient). The composition orformulation should suit the mode of administration.

As used herein, the term “excipient” refers to an inert substance whichis commonly used as a diluent, vehicle, preservative, binder, orstabilizing agent, and includes, but is not limited to, proteins (e.g.,serum albumin, etc.), amino acids (e.g., aspartic acid, glutamic acid,lysine, arginine, glycine, histidine, etc.), fatty acids andphospholipids (e.g., alkyl sulfonates, caprylate, etc.), surfactants(e.g., SDS, polysorbate, nonionic surfactant, etc.), saccharides (e.g.,sucrose, maltose, trehalose, etc.) and polyols (e.g., mannitol,sorbitol, etc.). See, also, for reference, Remington's PharmaceuticalSciences, (1990) Mack Publishing Co., Easton, Pa., which is herebyincorporated by reference in its entirety.

As used herein, the term “pharmaceutically acceptable” or“pharmacologically acceptable” refers to molecular entities,formulations and compositions that do not produce an adverse, allergic,or other untoward or unwanted reaction when administered, asappropriate, to an animal, such as a human. The preparation of apharmaceutical composition comprising an antibody or additional activeingredient are known to those of skill in the art in light of thepresent disclosure, as exemplified by Remington's PharmaceuticalSciences, Id. Moreover, for animal (e.g., human) administration, it willbe understood that preparations should meet sterility, pyrogenicity,general safety, and purity standards as required by a regulatory agencyof the Federal or a state government, such as the FDA Office ofBiological Standards or as listed in the U.S. Pharmacopeia, EuropeanPharmacopeia, or other generally recognized Pharmacopeia for use inanimals, and more particularly, in humans.

The term “pharmaceutical formulation” refers to a preparation which isin such form as to permit the biological activity of the activeingredient (e.g., an anti-PD-L1 antibody and an anti-glycPD-L1 antibody)to be effective, and which contains no additional components that wouldbe are unacceptably toxic to a subject to whom the formulation would beadministered. Such a formulation can be sterile, i.e., aseptic or freefrom all living microorganisms and their spores, etc.

The term “package insert” is used to refer to instructions customarilyincluded in commercial packages of therapeutic products, that containinformation about the indications, usage, dosage, administration,contraindications and/or warnings concerning the use of such therapeuticproducts.

As used herein, the term “treat,” “treatment,” or “treating” refers toadministration or application of a therapeutic agent to a subject inneed thereof, or performance of a procedure or modality on a subject,for the purpose of obtaining at least one positive therapeutic effect orbenefit, such as treating a disease or health-related condition. Forexample, a treatment can include administration of a pharmaceuticallyeffective amount of an antibody, or a composition or formulationthereof, that specifically binds to glycosylated PD-L1 for the purposeof treating various types of cancer. The terms “treatment regimen,”“dosing regimen,” or “dosing protocol,” are used interchangeably andrefer to the timing and dose of a therapeutic agent, such as ananti-glycPD-L1 antibody as described herein. As used herein, the term“subject” refers to either a human or a non-human animal, such asprimates, mammals, and vertebrates having a cancer or diagnosed with acancer. In preferred embodiments, the subject is a human. In someembodiments, the subject is a cancer patient. In an embodiment, thesubject in need will or is predicted to benefit from anti-glycPD-L1antibody treatment.

As used herein, the term “therapeutic benefit” or “therapeuticallyeffective” refers the promotion or enhancement of the well-being of asubject in need (e.g., a subject with a cancer or diagnosed with acancer) with respect to the medical treatment, therapy, dosageadministration, of a condition, particularly as a result of the use ofthe anti-glycPD-L1 antibodies and the performance of the describedmethods. This includes, but is not limited to, a reduction in thefrequency or severity of the signs or symptoms of a disease. Forexample, treatment of a cancer may involve, for example, a reduction inthe size of a tumor, a reduction in the invasiveness or severity of atumor, a reduction infiltration of cancer cells into a peripheral tissueor organ; a reduction in the growth rate of the tumor or cancer, or theprevention or reduction of metastasis. Treatment of cancer may alsorefer to achieving a sustained response in a subject or prolonging thesurvival of a subject with cancer.

As used herein, the term “administer” or “administration” refers to theact of physically delivering, e.g., via injection or an oral route, asubstance as it exists outside the body into a patient, such as by oral,subcutaneous, mucosal, intradermal, intravenous, intramuscular deliveryand/or any other method of physical delivery described herein or knownin the art. When a disease, disorder or condition, or a symptom thereof,is being treated therapeutically, administration of the substancetypically occurs after the onset of the disease, disorder or conditionor symptoms thereof. Prophylactic treatment involves the administrationof the substance at a time prior to the onset of the disease, disorderor condition or symptoms thereof.

As used herein, the term “effective amount” refers to the quantity oramount of a therapeutic (e.g., an antibody or pharmaceutical compositionprovided herein) which is sufficient to reduce, diminish, alleviate,and/or ameliorate the severity and/or duration of a cancer or a symptomrelated thereto. This term also encompasses an amount necessary for thereduction or amelioration of the advancement or progression of a cancer;the reduction or amelioration of the recurrence, development, or onsetof a cancer; and/or the improvement or enhancement of the prophylacticor therapeutic effect(s) of another cancer therapy (e.g., a therapyother than administration of an anti-PD-L1 antibody or anti-glycPD-L1antibody provided herein). In some embodiments, the effective amount ofan antibody provided herein is from about or equal to 0.1 mg/kg (mg ofantibody per kg weight of the subject) to about or equal to 100 mg/kg.In certain embodiments, an effective amount of an antibody providedtherein is about or equal to 0.1 mg/kg, about or equal to 0.5 mg/kg,about or equal to 1 mg/kg, about or equal to 3 mg/kg, about or equal to5 mg/kg, about or equal to 10 mg/kg, about or equal to 15 mg/kg, aboutor equal to 20 mg/kg, about or equal to 25 mg/kg, about or equal to 30mg/kg, about or equal to 35 mg/kg, about or equal to 40 mg/kg, about orequal to 45 mg/kg, about or equal to 50 mg/kg, about or equal to 60mg/kg, about or equal to 70 mg/kg, 80 mg/kg, 90 mg/kg, or 100 mg/kg.These amounts are meant to include amounts and ranges therein. In someembodiments, “effective amount” also refers to the amount of an antibodyprovided herein to achieve a specified result (e.g., preventing,blocking, or inhibiting cell surface PD-1 binding to cell surface PD-L1;or preventing, blocking, or inhibiting PD-1/PD-L1 mediatedimmunosuppression).

The term “in combination” in the context of the administration of othertherapies (e.g., other agents, cancer drugs, cancer therapies) includesthe use of more than one therapy (e.g., drug therapy and/or cancertherapy). Administration “in combination with” one or more furthertherapeutic agents includes simultaneous (e.g., concurrent) andconsecutive administration in any order. The use of the term “incombination” does not restrict the order in which therapies areadministered to a subject. By way of nonlimiting example, a firsttherapy (e.g., agent, such as an anti-glycPD-L1 antibody) may beadministered before (e.g., 1 minute, 15 minutes, 30 minutes, 45 minutes,1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours,12 hours, 24 hours, 48 hours, 72 hours, 96 hours, 1 week, 2 weeks, 3weeks, 4 weeks, 5 weeks, 6 weeks, 8 weeks, 8 weeks, 9 weeks, 10 weeks,11 weeks, or 12 weeks), concurrently, or after (e.g., 1 minute, 15minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5hours, 6 hours, 7 hours, 8 hours, 12 hours, 24 hours, 48 hours, 72hours, 96 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7weeks, 8 weeks, 9 weeks, 10 weeks, 11 weeks, or 12 weeks or longer) theadministration of a second therapy (e.g., agent) to a subject having ordiagnosed with a cancer.

The combination of therapies (e.g., use of agents, including therapeuticagents) may be more effective than the additive effects of any two ormore single therapy (e.g., have a synergistic effect). A synergisticeffect is typically unexpected and cannot be predicted. For example, asynergistic effect of a combination of therapeutic agents frequentlypermits the use of lower dosages of one or more of the agents and/orless frequent administration of the agents to a cancer patient. Theability to utilize lower dosages of therapeutics and cancer therapiesand/or to administer the therapies less frequently reduces the potentialfor toxicity associated with the administration of the therapies to asubject without reducing the effectiveness of the therapies. Inaddition, a synergistic effect may result in improved efficacy oftherapies in the treatment or alleviation of a cancer. Also, asynergistic effect demonstrated by a combination of therapies (e.g.,therapeutic agents) may avoid or reduce adverse or unwanted side effectsassociated with the use of any single therapy.

Anti-Glycosylated PD-L1 Antibodies (Anti-glycPD-L1 Antibodies)

Provided in embodiments are antibodies or binding fragments thereof thatbind to glycosylated PD-L1 protein (e.g., a PD-L1 protein having aspecific N-glycan structure; specific glycopeptides of PD-L1) orglycosylated PD-L1 peptides, preferably, with higher affinity than(i.e., preferentially bind) to unglycosylated PD-L1, and inhibit theimmune suppressive function of the glycosylated PD-L1/PD-1 interaction,as well as the use of such antibodies in the treatment of disease,particularly cancer. The anti-glycPD-L1 antibodies may of the IgG, IgM,IgA, IgD, and IgE Ig classes, as well as polypeptides comprising one ormore antibody CDR domains that retain antigen binding activity.Illustratively, the anti-glycPD-L1 antibodies may be chimeric, affinitymatured, humanized, or human antibodies. The anti-glycPD-L1 antibodiesare monoclonal antibodies. In certain embodiments, the monoclonalanti-glycPD-L1 antibodies are STM004 or STM115, or, humanized orchimeric forms thereof. In another preferred embodiment, the monoclonalanti-glycPD-L1 antibody is a humanized antibody. By known means and asdescribed herein, polyclonal or monoclonal antibodies, antibodyfragments, binding domains and CDRs (including engineered forms of anyof the foregoing) may be created that are specific for glycosylatedPD-L1 antigen, one or more of its respective epitopes, or conjugates ofany of the foregoing, whether such antigens or epitopes are isolatedfrom natural sources or are synthetic derivatives or variants of thenatural protein.

In an embodiment, the antibody is a chimeric antibody, for example, anantibody comprising antigen binding sequences (e.g., V domains and/orCDRs) from a non-human donor grafted to a heterologous non-human, humanor humanized sequence (e.g., framework and/or constant domainsequences). In one embodiment, the non-human donor sequences are frommouse or rat. In one embodiment, an antigen binding sequence issynthetic, e.g., obtained by mutagenesis (e.g., phage display screeningof a human phage library, etc.). In one embodiment, a chimeric antibodyhas murine V regions and human C regions. In one embodiment, the murinelight chain V region is fused to a human kappa light chain C region. Inone embodiment, the murine heavy chain V region is fused to a human IgG1C region.

In an embodiment, the antibody is an immunoglobulin single variabledomain derived from a camelid antibody, preferably from a heavy chaincamelid antibody, devoid of light chains, which are known as V_(H)Hdomain sequences or Nanobodies™. A Nanobody™ (Nb) is the smallestfunctional fragment or single variable domain (V_(H)H) of a naturallyoccurring single-chain antibody and is known to the person skilled inthe art. They are derived from heavy chain only antibodies seen incamelids (Hamers-Casterman et al., 1993, Nature, 363, p. 446-448;Desmyter et al., 1996, Nat. Struct. Biol., p. 803-811). In the family of“camelids,” immunoglobulins devoid of light polypeptide chains arefound. “Camelids” comprise old world camelids (Camelus bactrianus andCamelus dromedarius) and new world camelids (for example, Lama paccos,Lama glama, Lama guanicoe and Lama vicugna). The single variable domainheavy chain antibody is herein designated as a Nanobody™ or a V_(H)Hantibody. The small size and unique biophysical properties of Nbs excelconventional antibody fragments for the recognition of uncommon orhidden epitopes and for binding into cavities or active sites of proteintargets. Further, Nbs can be designed as multi-specific and multivalentantibodies, attached to reporter molecules, or humanized. Nbs arestable, survive the gastro-intestinal system and can easily bemanufactured.

In another embodiment, the antibody is a bispecific antibody. Unifyingtwo antigen binding sites of different specificity into a singleconstruct, bispecific antibodies have the ability to bring together twodiscreet antigens with exquisite specificity and therefore have greatpotential as therapeutic agents. Bispecific antibodies were originallymade by fusing two hybridomas, each capable of producing a differentimmunoglobulin. Bispecific antibodies are also produced by joining twoscFv antibody fragments while omitting the Fc portion present in fullimmunoglobulins. Each scFv unit in such constructs can contain onevariable domain from each of the heavy (V_(H)) and light (V_(L))antibody chains, joined with one another via a synthetic polypeptidelinker, the latter often being genetically engineered so as to beminimally immunogenic while remaining maximally resistant toproteolysis. Respective scFv units may be joined by a number of knowntechniques, including incorporation of a short (usually less than 10amino acids) polypeptide spacer bridging the two scFv units, therebycreating a bispecific single chain antibody. The resulting bispecificsingle chain antibody is therefore a species containing two V_(H)/V_(L)pairs of different specificity on a single polypeptide chain, in whichthe V_(H) and V_(L) domains in a respective scFv unit are separated by apolypeptide linker long enough to allow intramolecular associationbetween these two domains, such that the so-formed scFv units arecontiguously tethered to one another through a polypeptide spacer keptshort enough to prevent unwanted association between, for example, theV_(H) domain of one scFv unit and the V_(L) of the other scFv unit.

Examples of antibody fragments suitable for use include, withoutlimitation: (i) the Fab fragment, consisting of V_(L), V_(H), C_(L), andC_(H1) domains; (ii) the “Fd” fragment consisting of the V_(H) andC_(H1) domains; (iii) the “Fv” fragment consisting of the V_(L) andV_(H) domains of a single antibody; (iv) the “dAb” fragment, whichconsists of a V_(H) domain; (v) isolated CDR regions; (vi) F(ab′)2fragments, a bivalent fragment comprising two linked Fab fragments;(vii) single chain Fv molecules (“scFv”), in which a V_(H) domain and aV_(L) domain are linked by a peptide linker that allows the two domainsto associate to form a binding domain; (viii) bi-specific single chainFv dimers (see U.S. Pat. No. 5,091,513); and (ix) diabodies,multivalent, or multispecific fragments constructed by gene fusion (U.S.Patent Appln. Pub. No. 20050214860). Fv, scFv, or diabody molecules maybe stabilized by the incorporation of disulfide bridges linking theV_(H) and V_(L) domains. Minibodies comprising a scFv joined to a C_(H3)domain (Hu et al., 1996, Cancer Res., 56:3055-3061) may also be useful.In addition, antibody-like binding peptidomimetics are also contemplatedin embodiments. “Antibody like binding peptidomimetics” (ABiPs), whichare peptides that act as pared-down antibodies and have certainadvantages of longer serum half-life as well as less cumbersomesynthesis methods, have been reported by Liu et al., 2003, Cell Mol.Biol., 49:209-216.

Animals may be inoculated with an antigen, such as a glycosylated PD-L1polypeptide or peptide to generate an immune response and produceantibodies specific for the glycosylated PD-L1 polypeptide. Frequently,an antigen is bound or conjugated to another molecule to enhance theimmune response. As used herein, a conjugate is any peptide,polypeptide, protein, or non-proteinaceous substance bound to an antigenthat is used to elicit an immune response in an animal. Antibodiesproduced in an animal in response to antigen inoculation comprise avariety of non-identical molecules (polyclonal antibodies) made from avariety of individual antibody producing B lymphocytes. A polyclonalantibody is a mixed population of antibody species, each of which mayrecognize a different epitope on the same antigen. Given the correctconditions for polyclonal antibody production in an animal, most of theantibodies in the animal's serum will recognize the collective epitopeson the antigenic compound to which the animal has been immunized. Thisspecificity is further enhanced by affinity purification to select onlythose antibodies that recognize the antigen or epitope of interest.

A monoclonal antibody is a single, clonal species of antibody whereinevery antibody molecule recognizes the same epitope because all antibodyproducing cells are derived from a single, antibody-producingB-lymphocyte (or other clonal cell, such as a cell that recombinantlyexpresses the antibody molecule). The methods for generating monoclonalantibodies (MAbs) generally begin along the same lines as those forpreparing polyclonal antibodies. In some embodiments, rodents such asmice and rats are used in generating monoclonal antibodies. In someembodiments, rabbit, sheep, or frog cells are used in generatingmonoclonal antibodies. The use of rats is well known and may providecertain advantages. Mice (e.g., BALB/c mice) are routinely used andgenerally give a high percentage of stable fusions. Hybridoma technologyas used in monoclonal antibody production involves the fusion of asingle, antibody-producing B lymphocyte isolated from a mouse previouslyimmunized with a glycosylated PD-L1 protein or peptide with animmortalized myeloma cell, e.g., a mouse myeloma cell line. Thistechnology provides a method to propagate a single antibody-producingcell for an indefinite number of generations, such that unlimitedquantities of structurally identical antibodies having the same antigenor epitope specificity, i.e., monoclonal antibodies, may be produced.

Methods have been developed to replace light and heavy chain constantdomains of the monoclonal antibody with analogous domains of humanorigin, leaving the variable regions of the foreign antibody intact.Alternatively, “fully human” monoclonal antibodies are produced in miceor rats that are transgenic for human immunoglobulin genes. Methods havealso been developed to convert variable domains of monoclonal antibodiesto more human form by recombinantly constructing antibody variabledomains having both rodent and human amino acid sequences. In“humanized” monoclonal antibodies, only the hypervariable CDRs arederived from non-human (e.g., mouse, rat, chicken, llama, etc.)monoclonal antibodies, and the framework regions are derived from humanantibody amino acid sequences. The replacement of amino acid sequencesin the antibody that are characteristic of rodents with amino acidsequences found in the corresponding positions of human antibodiesreduces the likelihood of adverse immune reaction to foreign proteinduring therapeutic use in humans. A hybridoma or other cell producing anantibody may also be subject to genetic mutation or other changes, whichmay or may not alter the binding specificity of antibodies produced bythe hybridoma.

Engineered antibodies may be created using monoclonal and otherantibodies and recombinant DNA technology to produce other antibodies orchimeric molecules that retain the antigen or epitope bindingspecificity of the original antibody, i.e., the molecule has a specificbinding domain. Such techniques may involve introducing DNA encoding theimmunoglobulin variable region or the CDRs of an antibody into thegenetic material for the framework regions, constant regions, orconstant regions plus framework regions, of a different antibody. See,for instance, U.S. Pat. Nos. 5,091,513 and 6,881,557, which areincorporated herein by reference.

By known means as described herein, polyclonal or monoclonal antibodies,antibody fragments having binding activity, binding domains and CDRs(including engineered forms of any of the foregoing), may be createdthat specifically bind to glycosylated PD-L1 protein, one or more of itsrespective epitopes, or conjugates of any of the foregoing, whether suchantigens or epitopes are isolated from natural sources or are syntheticderivatives or variants of the natural compounds.

Antibodies may be produced from any animal source, including birds andmammals. Preferably, the antibodies are ovine, murine (e.g., mouse andrat), rabbit, goat, guinea pig, camel, horse, or chicken. In addition,newer technology permits the development of and screening for humanantibodies from human combinatorial antibody libraries. For example,bacteriophage antibody expression technology allows specific antibodiesto be produced in the absence of animal immunization, as described inU.S. Pat. No. 6,946,546, which is incorporated herein by reference.These techniques are further described in Marks et al., 1992,Bio/Technol., 10:779-783; Stemmer, 1994, Nature, 370:389-391; Gram etal., 1992, Proc. Natl. Acad. Sci. USA, 89:3576-3580; Barbas et al.,1994, Proc. Natl. Acad. Sci. USA, 91:3809-3813; and Schier et al., 1996,Gene, 169(2):147-155.

Methods for producing polyclonal antibodies in various animal species,as well as for producing monoclonal antibodies of various types,including humanized, chimeric, and fully human, are well known in theart and are highly reproducible. For example, the following U.S. patentsprovide descriptions of such methods and are herein incorporated byreference: U.S. Pat. Nos. 3,817,837; 3,850,752; 3,939,350; 3,996,345;4,196,265; 4,275,149; 4,277,437; 4,366,241; 4,469,797; 4,472,509;4,606,855; 4,703,003; 4,742,159; 4,767,720; 4,816,567; 4,867,973;4,938,948; 4,946,778; 5,021,236; 5,164,296; 5,196,066; 5,223,409;5,403,484; 5,420,253; 5,565,332; 5,571,698; 5,627,052; 5,656,434;5,770,376; 5,789,208; 5,821,337; 5,844,091; 5,858,657; 5,861,155;5,871,907; 5,969,108; 6,054,297; 6,165,464; 6,365,157; 6,406,867;6,709,659; 6,709,873; 6,753,407; 6,814,965; 6,849,259; 6,861,572;6,875,434; 6,891,024; 7,407,659; and 8,178,098.

It is expected that antibodies directed to glycosylated PD-L1 asdescribed herein will have the ability to neutralize, block, inhibit, orcounteract the effects of glycosylated PD-L1 regardless of the animalspecies, monoclonal cell line or other source of the antibody. Certainanimal species may be less preferable for generating therapeuticantibodies because they may be more likely to cause an immune orallergic response due to activation of the complement system through the“Fc” portion of the antibody. However, whole antibodies may beenzymatically digested into the “Fc” (complement binding) fragment, andinto peptide fragments having the binding domains or CDRs. Removal ofthe Fc portion reduces the likelihood that this antibody fragment willelicit an undesirable immunological response and, thus, antibodieswithout an Fc portion may be preferential for prophylactic ortherapeutic treatments. As described above, antibodies may also beconstructed so as to be chimeric, humanized, or partially or fullyhuman, so as to reduce or eliminate potential adverse immunologicaleffects resulting from administering to an animal an antibody that hasbeen produced in, or has amino acid sequences from, another species.

Substitutional variants typically contain the exchange of one amino acidfor another at one or more sites within the protein, and may be designedto modulate one or more properties of the polypeptide, with or withoutthe loss of other functions or properties. Substitutions may beconservative, that is, one amino acid is replaced with one of similarshape and charge. Conservative substitutions are as described in Table1, supra. Alternatively, substitutions may be non-conservative such thata function or activity of the polypeptide is affected. Non-conservativechanges typically involve substituting a residue with one that ischemically dissimilar, such as a polar or charged amino acid for anonpolar or uncharged amino acid, and vice versa.

Antibody proteins may be recombinant, or synthesized in vitro. It iscontemplated that in anti-glycPD-L1 antibody-containing compositions asdescribed herein there is between about 0.001 mg and about 10 mg oftotal antibody polypeptide per ml. Thus, the concentration of antibodyprotein in a composition can be about, at least about or at most aboutor equal to 0.001, 0.010, 0.050, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8,0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0,7.5, 8.0, 8.5, 9.0, 9.5, 10.0 mg/ml or more (or any range derivabletherein). Of this, about, at least about, at most about, or equal to 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75,76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93,94, 95, 96, 97, 98, 99, or 100% may be an antibody that bindsglycosylated PD-L1.

An antibody or an immunological portion of an antibody that retainsbinding activity, can be chemically conjugated to, or recombinantlyexpressed as, a fusion protein with other proteins. For the purposes asdescribed herein, all such fused proteins are included in the definitionof antibodies or an immunological portion of an antibody. In someembodiments, antibodies and antibody-like molecules generated againstglycosylated PD-L1, or polypeptides that are linked to at least oneagent to form an antibody conjugate or payload are encompassed. In orderto increase the efficacy of antibody molecules as diagnostic ortherapeutic agents, it is conventional to link or covalently bind orcomplex at least one desired molecule or moiety to the antibody. Such alinked molecule or moiety may be, but is not limited to, at least oneeffector or reporter molecule. Effector molecules comprise moleculeshaving a desired activity, e.g., cytotoxic activity. Non-limitingexamples of effector molecules that may be attached to antibodiesinclude toxins, therapeutic enzymes, antibiotics, radio-labelednucleotides and the like. By contrast, a reporter molecule is defined asany moiety that may be detected using an assay. Non-limiting examples ofreporter molecules that may be conjugated to antibodies include enzymes,radiolabel s, haptens, fluorescent labels, phosphorescent molecules,chemiluminescent molecules, chromophores, luminescent molecules,photoaffinity molecules, colored particles or ligands, such as biotin,and the like. Several methods are known in the art for attaching orconjugating an antibody to a conjugate molecule or moiety. Someattachment methods involve the use of a metal chelate complex, employingby way of nonlimiting example, an organic chelating agent such adiethylenetriaminepentaacetic acid anhydride (DTPA);ethylenetriaminetetraacetic acid; N-chloro-p-toluenesulfonamide; and/ortetrachloro-3-6α-diphenylglycouril-3 attached to the antibody.Antibodies, particularly the monoclonal antibodies as described herein,may also be reacted with an enzyme in the presence of a coupling agentsuch as glutaraldehyde or periodate. Conjugates with fluorescein markersare conventionally prepared in the presence of these coupling agents orby reaction with an isothiocyanate. In another embodiment, ananti-glycPD-L1 antibody as described herein, particularly a bindingfragment thereof, may be coupled or linked to a compound or substance,such as polyethylene glycol (PEG), to increase its in vivo half-life inplasma, serum, or blood following administration.

Provided in a particular embodiment are antibodies, such as monoclonalantibodies, that specifically and preferentially bind glycosylated PD-L1protein relative to non-glycosylated PD-L1 protein. In an embodiment,the anti-glycPD-L1 antibody specifically or preferentially binds toPD-L1 protein that is glycosylated at positions N35, N192, N200 and/orN219 of the amino acid sequence of the PD-L1 protein, e.g., as set forthin SEQ ID NO: 1. Alternatively, the anti-glycPD-L1 antibody bindsproximal to one or more of N35, N192, N200 or N219 in three dimensionalspace and, for example, may mask or block the glycosylated residue orresidues. For example, specific or selective binding of theanti-glycPD-L1 antibody involves binding of the antibody to PD-L1antigen with a K_(d) less than half of the K_(d) exhibited relative tounglycosylated PD-L1. In an embodiment, the anti-glycPD-L1 antibodybinds to glycosylated PD-L1 protein with a K_(d) at least 5 times lessthan the K_(d) exhibited relative to unglycosylated PD-L1. In anembodiment, the anti-glycPD-L1 antibody binds to glycosylated PD-L1protein with a K_(d) at least 10 times less than the Kd exhibitedrelative to unglycosylated PD-L1. In an embodiment, in a cell flowcytometry binding assay as described in Example 5, the antibody exhibitsbinding as expressed as MFI to cells expressing WT PD-L1 that is 1.5times, 2 times, 3, times, 4 times, 5 times, 6 times, 7 times, 8 times, 9times or 10 times greater than the MFI for binding to cells expressingunglycosylated PD-L1.

A particular embodiment provides an antibody, or a binding fragmentthereof, specific for glycosylated PD-L1, which is the anti-glycPD-L1monoclonal antibody STM004. In other embodiments, the anti-glycPD-L1antibody specifically binds an epitope on PD-L1 corresponding to aminoacid residues at positions Y56, K62 and K75 of the human PD-L1 aminoacid sequence as set forth in SEQ ID NO: 1 herein. STM004 binds tonon-contiguous amino acids within PD-L1 and the epitope is aconformational epitope. The portion of the human PD-L1 polypeptideencompassing the STM004 MAb epitope has the sequenceLDLAALIVYWEMEDKNIIQFVHGEEDLKVQH (SEQ ID NO: 93). As shown herein, theamino acid residues Y56, K62 and K75, which comprise the epitoperecognized by MAb STM004, are underlined.

Another particular embodiment provides an antibody, or a bindingfragment thereof, specific for glycosylated PD-L1, which is theanti-glycPD-L1 monoclonal antibody STM115. In other embodiments, theanti-glycPD-L1 antibody specifically binds an epitope on PD-L1corresponding to amino acid residues at positions K62, H69 and K75 ofthe human PD-L1 amino acid sequence as set forth in SEQ ID NO: 1 herein.The portion of the human PD-L1 polypeptide encompassing the STM115 MAbepitope has the sequence DKNIIQFVHGEEDLKVQH within SEQ ID NO: 1. Asshown herein, the amino acid residues K62, H69 and K75, which comprisethe epitope recognized by MAb STM115, are underlined.

The nucleic acid (DNA) and corresponding amino acid sequences of theheavy and light chain variable (V) domains of the STM004 MAb are shownin Table 3 infra. Table 3 provides both the nucleotide and amino acidsequences of the mature (i.e., not containing the signal peptide) VH andVL domains of STM004 (SEQ ID NOS 2, 3, 10, and 11, respectively) and theV_(H) and V_(L) domain sequences containing the signal peptides (SEQ IDNOS: 85, 86, 87, and 88, respectively). In the heavy chain DNA andprotein V domain sequences of the signal sequence containing heavy andlight chain domains shown in Table 3, the amino terminal signal sequence(nucleotides 1-57 and amino acids 1-19 of the V_(H) domain andnucleotides 1-60 and amino acids 1-20 of the V_(L) domain, respectively)is represented in italicized font. Also shown in Table 3 are the STM004MAb heavy and light chain V domain CDRs, using both the Kabat andChothia numbering definitions.

In an embodiment, the anti-glycPD-L1 antibody that specifically andpreferentially binds glycosylated PD-L1 comprises a V_(H) domain of SEQID NO: 3 and a V_(L) domain of SEQ ID NO: 11. In an embodiment, theanti-glycPD-L1 antibody competes for specific binding to glycosylatedPD-L1 with an antibody comprising a V_(H) domain of SEQ ID NO: 3 and aV_(L) domain of SEQ ID NO: 11. In an embodiment, the anti-glycPD-L1antibody that specifically and preferentially binds glycosylated PD-L1comprises a V_(H) domain comprising Chothia CDRs 1-3 having amino acidsequences of SEQ ID NO: 4, SEQ ID NO: 6, and SEQ ID NO: 8, respectively,or Kabat CDRs 1-3 having amino acid sequences of SEQ ID NO: 5, SEQ IDNO: 7, and SEQ ID NO: 9, respectively, or a combination thereof. In anembodiment, the anti-glycPD-L1 antibody competes for specific binding toglycosylated PD-L1 with an antibody comprising a V_(H) domain comprisingChothia CDRs 1-3 having amino acid sequences of SEQ ID NO: 4, SEQ ID NO:6, and SEQ ID NO: 8, respectively, or Kabat CDRs 1-3 having amino acidsequences of SEQ ID NO: 5, SEQ ID NO: 7, and SEQ ID NO: 9, respectively,or a combination thereof. In an embodiment, the anti-glycPD-L1 antibodythat specifically and preferentially binds glycosylated PD-L1 comprisesa V_(L) domain comprising CDRs 1-3 having amino acid sequences of SEQ IDNO: 12, SEQ ID NO: 14, and SEQ ID NO: 16, respectively. In anembodiment, the anti-glycPD-L1 antibody competes for specific binding toglycosylated PD-L1 with an antibody comprising a V_(L) domain comprisingCDRs 1-3 having amino acid sequences of SEQ ID NO: 12, SEQ ID NO: 14,and SEQ ID NO: 16, respectively. In an embodiment, the anti-glycPD-L1antibody that specifically and preferentially binds glycosylated PD-L1comprises (a) a V_(H) domain comprising Chothia CDRs 1-3 having aminoacid sequences of SEQ ID NO: 4, SEQ ID NO: 6, and SEQ ID NO: 8,respectively, or Kabat CDRs 1-3 having amino acid sequences of SEQ IDNO: 5, SEQ ID NO: 7, and SEQ ID NO: 9, respectively, or a combinationthereof; and (b) a V_(L) domain comprising CDRs 1-3 having amino acidsequences of SEQ ID NO: 12, SEQ ID NO: 14, and SEQ ID NO: 16,respectively. In embodiments, the anti-glycPD-L1 antibody competes forspecific binding to glycosylated PD-L1 with an antibody comprising theabove-described V_(H) and V_(L) domains and the CDRs therein.

In an embodiment, the anti-glycPD-L1 antibody that specifically bindsglycosylated PD-L1 comprises a V_(H) domain that is 80%, 85%, 90%, 95%98% or 99% identical to the amino acid sequence of SEQ ID NO: 3 and/or aV_(L) domain that is 80%, 85%, 90%, 95% 98% or 99% identical to theamino acid sequence of SEQ ID NO: 11, and which inhibits or blocksbinding of glycosylated PD-L1 to PD-1. In an embodiment, theanti-glycPD-L1 antibody that specifically and preferentially bindsglycosylated PD-L1 comprises a V_(H) domain comprising CDRs 1-3 with atleast 1, 2, or all 3 CDRs having at least 1, 2, 3, 4 or 5 amino acidsubstitutions with respect to the amino acid sequences of SEQ ID NO: 4,SEQ ID NO: 6, and SEQ ID NO: 8, respectively, or amino acid sequences ofSEQ ID NO: 5, SEQ ID NO: 7, and SEQ ID NO: 9, respectively, whichanti-glycPD-L1 antibody blocks binding of glycosylated PD-L1 to PD-1. Inan embodiment, the anti-glycPD-L1 antibody that specifically andpreferentially binds glycosylated PD-L1 comprises a V_(L) domaincomprising CDRs 1-3 with at least 1, 2, or all 3 CDRs having at least 1,2, 3, 4 or 5 amino acid substitutions with respect to amino acidsequences of SEQ ID NO: 12, SEQ ID NO: 14, and SEQ ID NO: 16,respectively. In an embodiment, the anti-glycPD-L1 antibody thatspecifically and preferentially binds glycosylated PD-L1 comprises (a) aV_(H) domain comprising CDRs 1-3 with at least 1, 2, or all 3 CDRshaving at least 1, 2, 3, 4 or 5 amino acid substitutions with respect tothe amino acid sequences of SEQ ID NO: 4, SEQ ID NO: 6, and SEQ ID NO:8, respectively, or amino acid sequences of SEQ ID NO: 5, SEQ ID NO: 7,and SEQ ID NO: 9, respectively; and (b) a V_(L) domain comprising CDRs1-3 with at least 1, 2, or all 3 CDRs having at least 1, 2, 3, 4 or 5amino acid substitutions with respect to amino acid sequences of SEQ IDNO: 12, SEQ ID NO: 14, and SEQ ID NO: 16, respectively, which antibodyblocks binding of glycosylated PD-L1 to PD-1. Also provided arehumanized forms of STM004 using the AbM, Contact or IMGT defined CDRs,with human framework regions and, optionally, human constant domains.

The foregoing anti-glycPD-L1 antibodies bind to glycosylated PD-L1 witha K_(d) less than half of the K_(d) exhibited relative to unglycosylatedPD-L1. In an embodiment, the anti-glycPD-L1 antibodies binds toglycosylated PD-L1 protein with a K_(d) at least 5 times less than theK_(d) exhibited relative to unglycosylated PD-L1. In an embodiment, theanti-glycPD-L1 antibodies binds to glycosylated PD-L1 protein with a Kdat least 10 times less than the K_(d) exhibited relative tounglycosylated PD-L1 protein. In an embodiment, the binding affinity ofthe anti-glycPD-L1 antibody for glycosylated PD-L1 is from 5-20 nM orfrom 5-10 nM inclusive of the lower and upper values. In an embodiment,in a cell flow cytometry binding assay as described in Example 5, theantibody exhibits binding as expressed as MFI to cells expressing WTPD-L1 that is 1.5 times, 2 times, 3, times, 4 times, 5 times, 6 times, 7times, 8 times, 9 times or 10 times greater than the WI for binding tocells expressing unglycosylated PD-L1.

In an embodiment, the antibody inhibits the interaction of PD-1 withPD-L1, and particularly inhibits the interaction of PD-1 expressed byeffector T-cells with PD-L1, particularly, glycosylated PD-L1, expressedby tumor cells.

In another particular embodiment, an antibody, or a binding fragmentthereof, is provided that specifically and preferentially bindsglycosylated PD-L1 which is the anti-glycPD-L1 monoclonal antibodySTM115. The nucleic acid (DNA) and corresponding amino acid sequences ofthe mature heavy and light chain variable (V) domains (SEQ ID NOs: 18,19, 26 and 27) of the STM115 MAb are shown in Table 3 infra. The DNA andamino acid sequences of the unprocessed heavy and light chain V domainsequences (i.e., those containing a signal sequence at the N-terminal)are also shown in Table 3 (SEQ ID NOs: 89, 90, 91 and 92) and the aminoterminal signal sequence is represented in italicized font (nucleotides1-57 and amino acids 1-19 of the V_(H) domain and nucleotides 1-66 andamino acids 1-22 of the V_(L) domain). Also shown in Table 3 are theSTM115 MAb heavy and light chain V domain CDRs, according to both theKabat and Chothia definitions.

In an embodiment, the anti-glycPD-L1 antibody that specifically andpreferentially binds glycosylated PD-L1 comprises a V_(H) domain of theamino acid sequence of SEQ ID NO: 19 and a V_(L) domain of the aminoacid sequence of SEQ ID NO: 27. In an embodiment, the anti-glycPD-L1antibody competes for specific binding to glycosylated PD-L1 with anantibody comprising a V_(H) domain of the amino acid sequence of SEQ IDNO: 19 and a V_(L) domain of the amino acid sequence of SEQ ID NO: 27.In an embodiment, the anti-glycPD-L1 antibody that specifically andpreferentially binds glycosylated PD-L1 comprises a V_(H) domaincomprising Chothia CDRs1-3 having amino acid sequences of SEQ ID NO: 20,SEQ ID NO: 22, and SEQ ID NO: 24, respectively, or Kabat CDRs 1-3 havingamino acid sequences of SEQ ID NO: 21, SEQ ID NO: 23, and SEQ ID NO: 25,respectively, or a combination thereof. In an embodiment, theanti-glycPD-L1 antibody competes for specific binding to glycosylatedPD-L1 with an antibody comprising a V_(H) domain comprising Chothia CDRs1-3 with amino acid sequences of SEQ ID NO: 20, SEQ ID NO: 22, and SEQID NO: 24, respectively, or Kabat CDRs 1-3 with amino acid sequences ofSEQ ID NO: 21, SEQ ID NO: 23, and SEQ ID NO: 25, respectively, or acombination thereof. In an embodiment, the anti-glycPD-L1 antibody thatspecifically and preferentially binds glycosylated PD-L1 comprises aV_(L) domain comprising CDRs 1-3 having amino acid sequences of SEQ IDNO: 28, SEQ ID NO: 30, and SEQ ID NO: 32, respectively. In anembodiment, the anti-glycPD-L1 antibody competes for specific binding toglycosylated PD-L1 with an antibody comprising a V_(L) domain comprisingCDRs 1-3 having amino acid sequences of SEQ ID NO: 28, SEQ ID NO: 30,and SEQ ID NO: 32, respectively. In an embodiment, the anti-glycPD-L1antibody that specifically and preferentially binds glycosylated PD-L1comprises (a) a V_(H) domain comprising Chothia CDRs1-3 having aminoacid sequences of SEQ ID NO: 20, SEQ ID NO: 22, and SEQ ID NO: 24,respectively, or Kabat CDRs 1-3 having amino acid sequences of SEQ IDNO: 21, SEQ ID NO: 23, and SEQ ID NO: 25, respectively, or a combinationthereof; and (b) a V_(L) domain comprising CDRs 1-3 having amino acidsequences of SEQ ID NO: 28, SEQ ID NO: 30, and SEQ ID NO: 32,respectively. In embodiments, the anti-glycPD-L1 antibody competes forspecific binding to glycosylated PD-L1 with an antibody comprising theabove-described VH and VL domains and the CDRs therein.

In an embodiment, the anti-glycPD-L1 antibody that specifically andpreferentially binds glycosylated PD-L1 comprises a V_(H) domain that is80%, 85%, 90%, 95% 98% or 99% identical to the amino acid sequence ofSEQ ID NO: 19 and a V_(L) domain that is 80%, 85%, 90%, 95% 98% or 99%identical to the amino acid sequence of SEQ ID NO: 27. In an embodiment,the anti-glycPD-L1 antibody that specifically and preferentially bindsglycosylated PD-L1 comprises a V_(H) domain comprising CDRs 1-3 with atleast 1, 2, or all 3 CDRs having at least 1, 2, 3, 4 or 5 amino acidsubstitutions with respect to the amino acid sequences of SEQ ID NO: 20,SEQ ID NO: 22, and SEQ ID NO: 24, respectively, or CDRs 1-3 having aminoacid sequences of SEQ ID NO: 21, SEQ ID NO: 23, and SEQ ID NO: 25,respectively, or a combination thereof. In an embodiment, theanti-glycPD-L1 antibody that specifically and preferentially bindsglycosylated PD-L1 comprises a V_(L) domain comprising CDRs 1-3 with atleast 1, 2, or all 3 CDRs having at least 1, 2, 3, 4 or 5 amino acidsubstitutions with respect to the amino acid sequences of SEQ ID NO: 28,SEQ ID NO: 30, and SEQ ID NO: 32, respectively. In an embodiment, theanti-glycPD-L1 antibody that specifically and preferentially bindsglycosylated PD-L1 comprises (a) a V_(H) domain comprising CDRs 1-3 withat least 1, 2, or all 3 CDRs having at least 1, 2, 3, 4 or 5 amino acidsubstitutions with respect to the amino acid sequences of SEQ ID NO: 20,SEQ ID NO: 22, and SEQ ID NO: 24, respectively, or with respect to theamino acid sequences of SEQ ID NO: 21, SEQ ID NO: 23, and SEQ ID NO: 25,respectively, or a combination thereof; and/or (b) a V_(L) domaincomprising CDRs 1-3 with at least 1, 2, or all 3 CDRs having at least 1,2, 3, 4 or 5 amino acid substitutions with respect to the amino acidsequences of SEQ ID NO: 28, SEQ ID NO: 30, and SEQ ID NO: 32,respectively. Also provided are humanized forms of STM115 using the AbM,Contact or IMGT defined CDRs, with human framework regions and,optionally, human constant domains.

In embodiments, the foregoing anti-glycPD-L1 antibodies bind toglycosylated PD-L1 with a K_(d) less than half of the K_(d) exhibitedrelative to unglycosylated PD-L1. In an embodiment, the anti-glycPD-L1antibodies bind to glycosylated PD-L1 protein with a K_(d) at least 5times less than the K_(d) exhibited relative to unglycosylated PD-L1. Inan embodiment, the anti-glycPD-L1 antibody binds to glycosylated PD-L1protein with a K_(d) at least 10 times less than the K_(d) exhibitedrelative to unglycosylated PD-L1 protein. In an embodiment, the bindingaffinity of STM115 MAb for glycosylated PD-L1 is from 5-20 nM or from5-10 nM inclusive of the lower and upper values. In an embodiment, in acell flow cytometry binding assay as described in Example 5, theantibody exhibits binding as expressed as MFI to cells expressing WTPD-L1 that is 1.5 times, 2 times, 3, times, 4 times, 5 times, 6 times, 7times, 8 times, 9 times or 10 times greater than the MFI for binding tocells expressing unglycosylated PD-L1. These anti-glycPD-L1 antibodiesinhibit the interaction of PD-1 with PD-L1, and particularly inhibit theinteraction of PD-1 expressed by effector T-cells with PD-L1,particularly, glycosylated PD-L1, expressed by tumor cells.

Another embodiment provides an isolated anti-glycPD-L1 antibody or abinding fragment thereof, that binds glycosylated PD-L1 and competes orcross competes for specific binding to glycosylated PD-L1 with MAbSTM004 or MAb STM115 as described herein, when assayed via conventionalcompetition methods. In an aspect, an isolated antibody, e.g., amonoclonal antibody, or binding fragment thereof that binds the sameepitope as MAb STM004 or MAb STM115 is provided.

Another embodiment provides an isolated anti-glycPD-L1 antibody thatspecifically binds to an epitope within an amino acid sequence selectedfrom LDLAALIVYWEMEDKNIIQFVHGEEDLKVQH (SEQ ID NO: 93), which sequence islocated within the mature human PD-L1 polypeptide sequence of SEQ ID NO:1.

Another embodiment provides an isolated anti-glycPD-L1 antibody thatbinds to an epitope comprising amino acid residues Y56, K62 and K75 ofthe human PD-L1 protein of SEQ ID NO: 1. In an aspect, an isolatedanti-glycPD-L1 antibody that specifically binds glycosylated human PD-L1at an epitope comprising at least one of the following amino acidresidues: Y56, K62, or K75 of SEQ ID NO: 1 is provided. Anotherembodiment provides an isolated anti-glycPD-L1 antibody that binds to anepitope comprising amino acid residues K62, H69 and K75 of the humanPD-L1 protein of SEQ ID NO: 1. In an aspect, an isolated anti-glycPD-L1antibody that specifically binds glycosylated human PD-L1 at an epitopecomprising at least one of the following amino acid residues: K62, H69,or K75 of SEQ ID NO: 1 is provided. In embodiments, the anti-glycPD-L1antibody contacts at least two, at least three, or four of the aminoacid residues comprising the epitope region(s) of PD-L1, i.e.,glycosylated human PD-L1.

Yet another embodiment provides an isolated anti-glycPD-L1 antibody thatspecifically binds glycosylated human PD-L1 at an epitope including atleast one amino acid within the amino acid region from L48 to H78 orwithin the amino acid region from D61 to H78 of SEQ ID NO: 1. In anembodiment, an isolated anti-glycPD-L1 antibody that specifically bindsglycosylated human PD-L1 at an epitope that includes the following groupof amino acid residues: Y56, K62, K75 within the amino acid region fromL48 to H78 of SEQ ID NO: 1 is provided. In another embodiment, anisolated anti-glycPD-L1 antibody that specifically binds glycosylatedhuman PD-L1 at an epitope that includes the following group of aminoacid residues: K62, H69, K75 within the amino acid region from L48 toH78 or within the amino acid region from D61 to H78 of SEQ ID NO: 1 isprovided.

Yet another embodiment provides an isolated nucleic acid moleculeencoding an anti-glycPD-L1 V_(H) domain comprising a nucleotide sequencethat is at least 90-98% identical to SEQ ID NOs: 2 or 18 and/or encodingan anti-glycPD-L1 antibody V_(L) domain comprising a nucleotide sequencethat is at least 90-98% identical to SEQ ID NO: 10, or 26, respectively.In embodiments, the nucleotide sequences encoding the V_(H) and/or theV_(L) domains are 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, ormore identical to SEQ ID NOs: 2 or 18, or SEQ ID NOs: 10 or 26,respectively.

TABLE 3 Nucleotide and Amino Acid Sequences of anti-glycPD-L1 MAbsSEQ ID NO: Sequence Description SEQ ID NO: 2caggttcagctgcaacagtctgacgctgagttggt MAb STM004 mature heavygaaacctggggcttcagtgaagatatcctgcaagg chain V domain nucleotidecttctggctacaccttcagtgaccatgctattcac (DNA) sequencetgggtgaaacagaggcctgaacagggcctggaatg gattggatgtatttctcccggaagtggtgatattacttataatgagaaattcaagggcaaggccaccctg actgcagacaaatcctccagcactgcctacatgcagctcaacagcctgacatctgaggattctgcagtgt atttctgtaaaagatgggggcttgactactggggccaaggaaccactctcacagtctcctca SEQ ID NO: 3QVQLQQSDAELVKPGASVKISCKASGYTFSDHAIH MAb STM004 mature heavyWVKQRPEQGLEWIGCISPGSGDITYNEKFKGKATL chain V domain proteinTADKSSSTAYMQLNSLTSEDSAVYFCKRWGLDYWG sequence QGTTLTVSS SEQ ID NO: 4GYTFTDH MAb STM004 heavy chain V domain Chothia CDR1 SEQ ID NO: 5 DHAIHMAb STM004 heavy chain V domain Kabat CDR1 SEQ ID NO: 6 SPGSGDMAb STM004 heavy chain V domain Chothia CDR2 SEQ ID NO: 7CISPGSGDITYNEKFKG MAb STM004 heavy chain V domain Kabat CDR2SEQ ID NO: 8 WGLDY MAb STM004 heavy chain V domain Chothia CDR3SEQ ID NO: 9 KRWGLD MAb STM004 heavy chain V domain Kabat CDR3SEQ ID NO: 10 gacattgtgctcacccaatctccagcttctttggcMAb STM004 mature kappa tgtgtctctagggcagagagccaccatctcctgcalight chain V domain gagccagtgaaagtgttgaattttatggcacaactnucleotide (DNA) sequence ttaatgcagtggtaccaacagaaaccaggacagccacccagactcctcatctatgctgcatccaacgtag aatctggggtccctgccaggtttagtggcagtgggtctgggacagacttcagcctcaacatccatcctgt ggaggacgatgatattgcaatgtatttctgtcagcaaagtaggaaggttccgtacacgttcggagggggg accaagctggaaataaaa SEQ ID NO: 11DIVLTQSPASLAVSLGQRATISCRASESVEFYGTT MAb STM004 mature kappaLMQWYQQKPGQPPRLLIYAASNVESGVPARFSGSG light chain V domain proteinSGTDFSLNIHPVEDDDIAMYFCQQSRKVPYTFGGG sequence TKLEIK SEQ ID NO: 12RASESVEFYGTTLMQ MAb STM004 kappa light chain V domain Chothia CDR1SEQ ID NO: 13 RASESVEFYGTTLMQ MAb STM004 kappa lightchain V domain Kabat CDR1 SEQ ID NO: 14 AASNVES MAb STM004 kappa lightchain V domain Chothia CDR2 SEQ ID NO: 15 AASNVES MAb STM004 kappa lightchain V domain Kabat CDR2 SEQ ID NO: 16 QQSRKVPYT MAb STM004 kappa lightchain V domain Chothia CDR3 SEQ ID NO: 17 QQSRKVPYTMAb STM004 kappa light chain V domain Kabat CDR3 SEQ ID NO: 18gaagtgatgctggtggagtctgggggagccttagt MAb STM115 mature heavyggagcctggagggtccctgaaactctcctgtgtag chain V domain nucleotidecctctggattcactttcagtaactatgccatgtct (DNA) sequencetgggttcgccagactccagagaggaggctggagtg ggtcgcatccattactaatggtggtacttacacctactatccagacagtgtgaagggtcgattcaccatc tccagagacaatgccaggaacaccctgtacctccaaatgagcagtctgaggtctgaggacacggccatgt atttctgtgcaagaccgctccattactacggtggtagccactttgactactggggccaaggcaccactct cacggtctcctca SEQ ID NO: 19EVMLVESGGALVEPGGSLKLSCVASGFTFSNYAMS MAb STM115 heavy chain VWVRQTPERRLEWVASITNGGTYTYYPDSVKGRFTI domain protein sequenceSRDNARNTLYLQMSSLRSEDTAMYFCARPLHYYGG SHFDYWGQGTTLTVSS SEQ ID NO: 20GFTFSNY MAb STM115 heavy chain V domain Chothia CDR1 SEQ ID NO: 21 NYAMSMAb STM115 heavy chain V domain Kabat CDR1 SEQ ID NO: 22 TNGGTYMAb STM115 heavy chain V domain Chothia CDR2 SEQ ID NO: 23SITNGGTYTYYYPDSVKG MAb STM115 heavy chain V domain Kabat CDR2SEQ ID NO: 24 PLHYYGGSHFDY MAb STM115 heavy chain V domain Chothia CDR3SEQ ID NO: 25 PLHYYGGSHFDY MAb STM115 heavy chain V domain Kabat CDR3SEQ ID NO: 26 gaaattgtgctcacccagtctccagcactcatggcMAb STM115 mature kappa tgcatctccaggggagaaggtcaccatcacctgcalight chain V domain gtgtcagttcaagtataagttccaacactttgcacnucleotide (DNA) sequence tggtaccagcagaagtcagaaatttcccccaaaccctggatttatggcacatccaacctggcttctggag tccctgttcgcttcagtggcagtggatctgggacctcttattctctcacaatcagcagcatggaggctga agatgctgccacttattactgtcaacagtggagtagttacccactcacgttcggaggggggaccaagctg gaaataaaa SEQ ID NO: 27EIVLTQSPALMAASPGEKVTITCSVSSSISSNTLH MAb STM115 mature kappaWYQQKSEISPKPWIYGTSNLASGVPVRFSGSGSGT light chain V domain proteinSYSLTISSMEAEDAATYYCQQWSSYPLTFGGGTKL sequence EIK SEQ ID NO: 28SVSSISSNTLH MAb STM115 kappa light chain V domain Chothia CDR1SEQ ID NO: 29 SVSSISSNTLH MAb STM115 kappa lightchain V domain Kabat CDR1 SEQ ID NO: 30 GTSNLAS MAb STM115 kappa lightchain V domain Chothia CDR2 SEQ ID NO: 31 GTSNLAS MAb STM115 kappa lightchain V domain Kabat CDR2 SEQ ID NO: 32 QQWSSYPLT MAb STM115 kappa lightchain V domain Chothia CDR3 SEQ ID NO: 33 QQWSSYPLTMAb STM115 kappa light chain V domain Kabat CDR3 SEQ ID NO: 85

MAb STM004 heavy chain V

caggttcagctgc domain nucleotide (DNA)aacagtctgacgctgagttggtgaaacctggggct sequencetcagtgaagatatcctgcaaggcttctggctacac 5′ terminal nucleotides 1-57cttcagtgaccatgctattcactgggtgaaacaga denoted in italics encode theggcctgaacagggcctggaatggattggatgtatt signal sequencetctcccggaagtggtgatattacttataatgagaa attcaagggcaaggccaccctgactgcagacaaatcctccagcactgcctacatgcagctcaacagcctg acatctgaggattctgcagtgtatttctgtaaaagatgggggcttgactactggggccaaggaaccactc tcacagtctcctca SEQ ID NO: 86

QVQLQQSDAELVKPGA MAb STM004 heavy chain VSVKISCKASGYTFSDHAIHWVKQRPEQGLEWIGCI domain protein sequenceSPGSGDITYNEKFKGKATLTADKSSSTAYMQLNSL Amino terminal residues M1-TSEDSAVYFCKRWGLDYWGQGTTLTVSS S19 denoted in italicsconstitute the signal sequence SEQ ID NO: 87

MAb STM004 kappa light

gacattgtgc chain V domain nucleotide tcacccaatctccagcttctttggctgtgtctcta(DNA) sequence gggcagagagccaccatctcctgcagagccagtga 5′terminal nucleotides 1-60 aagtgttgaattttatggcacaactttaatgcagtdenoted in italics encode the ggtaccaacagaaaccaggacagccacccagactcsignal sequence ctcatctatgctgcatccaacgtagaatctggggtccctgccaggtttagtggcagtgggtctgggacag acttcagcctcaacatccatcctgtggaggacgatgatattgcaatgtatttctgtcagcaaagtaggaa ggttccgtacacgttcggaggggggaccaagctggaaataaaa SEQ ID NO: 88

DIVLTQSPASLAVSL MAb STM004 kappa lightGQRATISCRASESVEFYGTTLMQWYQQKPGQPPRL chain V domain proteinLIYAASNVESGVPARFSGSGSGTDFSLNIHPVEDD sequence DIAMYFCQQSRKVPYTFGGGTKLEIKAmino terminal residues M1- G20 denoted in italicsconstitute the signal sequence SEQ ID NO: 89

MAb STM115 heavy chain V

gaagtgatgctgg domain nucleotide (DNA)tggagtctgggggagccttagtggagcctggaggg sequencetccctgaaactctcctgtgtagcctctggattcac 5′ terminal nucleotides 1-57tttcagtaactatgccatgtcttgggttcgccaga denoted in italics encode thectccagagaggaggctggagtgggtcgcatccatt signal sequenceactaatggtggtacttacacctactatccagacag tgtgaagggtcgattcaccatctccagagacaatgccaggaacaccctgtacctccaaatgagcagtctg aggtctgaggacacggccatgtatttctgtgcaagaccgctccattactacggtggtagccactttgact actggggccaaggcaccactctcacggtctcctcaSEQ ID NO: 90

EVMLVESGGALVEPGG MAb STM115 heavy chain VSLKLSCVASGFTFSNYAMSWVRQTPERRLEWVASI domain protein sequenceTNGGTYTYYPDSVKGRFTISRDNARNTLYLQMSSL Amino terminal residues M1-RSEDTAMYFCARPLHYYGGSHFDYWGQGTTLTVSS C19 denoted in italicsconstitute the signal sequence SEQ ID NO: 91

MAb STM115 kappa light

gaaa chain V domain nucleotide ttgtgctcacccagtctccagcactcatggctgca(DNA) sequence tctccaggggagaaggtcaccatcacctgcagtgt 5′terminal nucleotides 1-66 cagttcaagtataagttccaacactttgcactggtdenoted in italics encode the accagcagaagtcagaaatttcccccaaaccctggsignal sequence atttatggcacatccaacctggcttctggagtccctgttcgcttcagtggcagtggatctgggacctctt attctctcacaatcagcagcatggaggctgaagatgctgccacttattactgtcaacagtggagtagtta cccactcacgttcggaggggggaccaagctggaaataaaa SEQ ID NO: 92

EIVLTQSPALMAA MAb STM115 kappa light SPGEKVTITCSVSSSISSNTLHWYQQKSEISPKPWchain V domain protein IYGTSNLASGVPVRFSGSGSGTSYSLTISSMEAED sequenceAATYYCQQWSSYPLTFGGGTKLEIK Amino terminal residues M1-G22 denoted in italics constitute the signal sequence

Disease Treatment

In certain aspects, an antibody or antigen binding fragment thereof, asdescribed in the embodiments herein (e.g., an antibody that specificallyand preferentially binds to glycosylated PD-L1 and blocks or inhibitsbinding of anti-PD-L1 to PD-1) may be used in treatment methods andadministered to treat a cancer. Accordingly, provided herein are methodsof treating a cancer by administering to a subject in need thereof atherapeutically effective amount of at least one anti-glycPD-L1 antibodyas described herein to treat the cancer. The subject is preferably ahuman patient. As noted herein, treatment or therapeutic treatmentinvolves reducing, preventing, inhibiting, or blocking the growth,proliferation, migration, etc., and, particularly, promoting cellkilling or apoptosis of cancer cells in the patient. The describedmethods provide a benefit to the subject, preferably, a human patient,undergoing treatment, with particular regard to a subject's tumor cellsthat express PD-L1 cell surface proteins that can bind/interact withPD-1 expressed on the cell surface of immune effector cells, such asT-cells, particularly, killer or cytotoxic T-cells.

Treatment of these subjects with an effective amount of at least one ofthe anti-glycPD-L1 antibodies as described herein is expected to resultin binding of the antibody(ies) to glycosylated PD-L1 on the tumor cellsand preventing, blocking, or inhibiting the interaction ofPD-L1-expressing tumor cells with PD-1-expressing T cells, therebypreventing or avoiding immunosuppression of T-cell activity and allowingT cells to be activated to kill the PD-L1-bearing tumor cells.Accordingly, the methods as provided are advantageous for a subject whois in need of, capable of benefiting from, or who is desirous ofreceiving the benefit of, the anti-cancer results achieved by thepractice of the present methods. A subject's seeking the therapeuticbenefits of the methods involving administration of at least oneanti-glycPD-L1 antibody in a therapeutically effective amount, orreceiving such therapeutic benefits offer advantages to the art. Inaddition, the present methods offer the further advantages ofeliminating or avoiding side effects, adverse outcomes,contraindications, and the like, or reducing the risk or potential forsuch issues to occur compared with other treatments and treatmentmodalities.

In certain embodiments, the methods comprise administration of two ormore different anti-glycPD-L1 antibodies as described herein.Co-administration of the anti-glycPD-L 1 antibodies may be moretherapeutically or prophylactically effective than administration ofeither antibody alone and/or may permit administration of a lower doseor with lower frequency than either antibody alone.

Cancers for which the present treatment methods are useful include anymalignant cell type, such as those found in a solid tumor or ahematological tumor. In general, a tumor refers to a malignant or apotentially malignant neoplasm or tissue mass of any size, and includesprimary tumors and secondary tumors. A solid tumor is an abnormal tissuemass or growth that usually does not contain cysts or liquid. Exemplarysolid tumors can include, but are not limited to, a tumor of an organselected from the group consisting of pancreas, gall bladder, colon,cecum, stomach, brain, head, neck, ovary, testes, kidney, larynx,sarcoma, lung, bladder, melanoma, prostate, and breast. Exemplaryhematological tumors include tumors of the bone marrow, T or B cellmalignancies, leukemias, lymphomas, blastomas, myelomas, and the like.Further examples of cancers that may be treated using the methodsprovided herein include, but are not limited to, carcinoma, lymphoma,blastoma, sarcoma, leukemia, squamous cell cancer, lung cancer(including small-cell lung cancer, non-small cell lung cancer,adenocarcinoma of the lung, and squamous carcinoma of the lung), cancerof the peritoneum, hepatocellular cancer, gastric or stomach cancer(including gastrointestinal cancer and gastrointestinal stromal cancer),pancreatic cancer, gall bladder cancer, glioblastoma, cervical cancer,ovarian cancer, liver cancer, bladder cancer, breast cancer, coloncancer, colorectal cancer, endometrial or uterine carcinoma, salivarygland carcinoma, kidney or renal cancer, prostate cancer, vulval cancer,thyroid cancer, various types of head and neck cancer, melanoma,superficial spreading melanoma, lentigo malignant melanoma, acrallentiginous melanomas, nodular melanomas, as well as B-cell lymphoma(including low grade/follicular non-Hodgkin's lymphoma (NHL); smalllymphocytic (SL) NHL; intermediate grade/follicular NHL; intermediategrade diffuse NHL; high grade immunoblastic NHL; high gradelymphoblastic NHL; high grade small non-cleaved cell NHL; bulky diseaseNHL; mantle cell lymphoma; AIDS-related lymphoma; and Waldenstrom'smacroglobulinemia), chronic lymphocytic leukemia (CLL), acutelymphoblastic leukemia (ALL), Hairy cell leukemia, multiple myeloma,acute myeloid leukemia (AML) and chronic myeloblastic leukemia.

The cancer may specifically be of the following histological types,though it need not be limited to these: neoplasm, malignant; carcinoma;carcinoma, undifferentiated; giant and spindle cell carcinoma; smallcell carcinoma; papillary carcinoma; squamous cell carcinoma;lymphoepithelial carcinoma; basal cell carcinoma; pilomatrix carcinoma;transitional cell carcinoma; papillary transitional cell carcinoma;adenocarcinoma; gastrinoma, malignant; cholangiocarcinoma;hepatocellular carcinoma; combined hepatocellular carcinoma andcholangiocarcinoma; trabecular adenocarcinoma; adenoid cystic carcinoma;adenocarcinoma in adenomatous polyp; adenocarcinoma, familial polyposiscoli; solid carcinoma; carcinoid tumor, malignant; branchiolo-alveolaradenocarcinoma; papillary adenocarcinoma; chromophobe carcinoma;acidophil carcinoma; oxyphilic adenocarcinoma; basophil carcinoma; clearcell adenocarcinoma; granular cell carcinoma; follicular adenocarcinoma;papillary and follicular adenocarcinoma; nonencapsulating sclerosingcarcinoma; adrenal cortical carcinoma; endometroid carcinoma; skinappendage carcinoma; apocrine adenocarcinoma; sebaceous adenocarcinoma;ceruminous adenocarcinoma; mucoepidermoid carcinoma; cystadenocarcinoma;papillary cystadenocarcinoma; papillary serous cystadenocarcinoma;mucinous cystadenocarcinoma; mucinous adenocarcinoma; signet ring cellcarcinoma; infiltrating duct carcinoma; medullary carcinoma; lobularcarcinoma; inflammatory carcinoma; Paget's disease, mammary; acinar cellcarcinoma; adenosquamous carcinoma; adenocarcinoma w/squamousmetaplasia; thymoma, malignant; ovarian stromal tumor, malignant;thecoma, malignant; granulosa cell tumor, malignant; androblastoma,malignant; sertoli cell carcinoma; leydig cell tumor, malignant; lipidcell tumor, malignant; paraganglioma, malignant; extra-mammaryparaganglioma, malignant; pheochromocytoma; glomangiosarcoma; malignantmelanoma; amelanotic melanoma; superficial spreading melanoma; malignantmelanoma in giant pigmented nevus; epithelioid cell melanoma; bluenevus, malignant; sarcoma; fibrosarcoma; fibrous hi stiocytoma,malignant; myxosarcoma; liposarcoma; leiomyosarcoma; rhabdomyosarcoma;embryonal rhabdomyosarcoma; alveolar rhabdomyosarcoma; stromal sarcoma;mixed tumor, malignant; mullerian mixed tumor; nephroblastoma;hepatoblastoma; carcinosarcoma; mesenchymoma, malignant; brenner tumor,malignant; phyllodes tumor, malignant; synovial sarcoma; mesothelioma,malignant; dysgerminoma; embryonal carcinoma; teratoma, malignant;struma ovarii, malignant; choriocarcinoma; mesonephroma, malignant;hemangiosarcoma; hemangioendothelioma, malignant; Kaposi's sarcoma;hemangiopericytoma, malignant; lymphangiosarcoma; osteosarcoma;juxtacortical osteosarcoma; chondrosarcoma; chondroblastoma, malignant;mesenchymal chondrosarcoma; giant cell tumor of bone; Ewing's sarcoma;odontogenic tumor, malignant; amyeloblastic odontosarcoma;ameloblastoma, malignant; ameloblastic fibrosarcoma; pinealoma,malignant; chordoma; glioma, malignant; ependymoma; astrocytoma;protoplasmic astrocytoma; fibrillary astrocytoma; astroblastoma;glioblastoma; oligodendroglioma; oligodendroblastoma; primitiveneuroectodermal; cerebellar sarcoma; ganglioneuroblastoma;neuroblastoma; retinoblastoma; olfactory neurogenic tumor; meningioma,malignant; neurofibrosarcoma; neurilemmoma, malignant; granular celltumor, malignant; malignant lymphoma; Hodgkin's disease; paragranuloma;malignant lymphoma, small lymphocytic; malignant lymphoma, large cell,diffuse; malignant lymphoma, follicular; mycosis fungoides; otherspecified non-Hodgkin's lymphomas; malignant histiocytosis; multiplemyeloma; mast cell sarcoma; immunoproliferative small intestinaldisease; leukemia; lymphoid leukemia; plasma cell leukemia;erythroleukemia; lymphosarcoma cell leukemia; myeloid leukemia;basophilic leukemia; eosinophilic leukemia; monocytic leukemia; mastcell leukemia; megakaryoblastic leukemia; myeloid sarcoma; and hairycell leukemia.

The cancer to be treated preferably is positive for PD-L1, particularlyglycosylated PD-L1. In certain embodiments, the tumor cells are alsopositive for a tumor cell marker such as EGFR or HER2/neu expression,for example for breast cancer. The presence or absence of these markersmay indicate that combination therapy with a targeted therapeutic, suchas a tyrosine kinase inhibitor such as gefitinib for EGFR positivecancer, or Herceptin for HER2/neu positive cancer, in combination withthe dual function anti-glycPD-L1 antibodies as described herein. Thus,certain embodiments provide methods of treatment of cancer that ispositive for glycosylated PD-L1 and a second cancer marker, such asEGFR, in a subject suffering therefrom comprising administering ananti-glycPD-L1 antibody as described in combination with a cancertherapeutic that targets the second cancer marker, for example, an EGFRtyrosine kinase inhibitor, such as gefitinib. Such combinations mayresult in improved therapeutic efficacy, including reduction in sideeffects, toxicity, etc. In certain embodiments, the cancer is a BLBC.

Other markers that may be used to characterize cancers to guide choiceof therapy or monitor therapy include ALK gene rearrangements andoverexpression in non-small cell lung cancer and anaplastic large celllymphoma; alpha-fetoprotein (AFP) for liver cancer and germ cell tumors;beta-2-microglobulin (B2M) for multiple myeloma, chronic lymphocyticleukemia, and some lymphomas; beta-human chorionic gonadotropin(Beta-hCG) for choriocarcinoma and germ cell tumors; BRCA1 and BRCA2gene mutations for ovarian cancer and breast cancer; BCR-ABL fusion gene(Philadelphia chromosome) for chronic myeloid leukemia, acutelymphoblastic leukemia, and acute myelogenous leukemia; BRAF V600mutations for cutaneous melanoma and colorectal cancer; C-kit/CD117 forgastrointestinal stromal tumor and mucosal melanoma; CA15-3/CA27.29 forbreast cancer; CA19-9 for pancreatic cancer, gallbladder cancer, bileduct cancer, and gastric cancer; CA-125 for ovarian cancer; calcitoninfor medullary thyroid cancer; carcinoembryonic antigen (CEA) forcolorectal cancer and some other cancers; CD20 for non-Hodgkin lymphoma;Chromogranin A (CgA) for neuroendocrine tumors; chromosomes 3, 7, 17,and 9p21 for bladder cancer; cytokeratin fragment 21-1 for lung cancer;EGFR gene mutation analysis for non-small cell lung cancer; estrogenreceptor (ER)/progesterone receptor (PR) for breast cancer;fibrin/fibrinogen for bladder cancer; HE4 for ovarian cancer; HER2/neugene amplification or protein overexpression for breast cancer, gastriccancer, and gastroesophageal junction adenocarcinoma; immunoglobulinsfor multiple myeloma and Waldenström macroglobulinemia; KRAS genemutation analysis for colorectal cancer and non-small cell lung cancer;lactate dehydrogenase for germ cell tumors, lymphoma, leukemia,melanoma, and neuroblastoma; neuron-specific enolase (NSE) for smallcell lung cancer and neuroblastoma; nuclear matrix protein 22 forbladder cancer; prostate-specific antigen (PSA) for prostate cancer;thyroglobulin for thyroid cancer; and urokinase plasminogen activator(uPA) and plasminogen activator inhibitor (PAI-1) for breast cancer.

The anti-glycPD-L1 antibodies, such as monoclonal antibodies, may beused as antitumor agents in a variety of modalities. A particularembodiment relates to methods of using an antibody as an antitumoragent, and therefore comprises contacting a population of tumor cellswith a therapeutically effective amount of the antibody, or acomposition containing the antibody, for a time period sufficient toblock or inhibit tumor cell growth. In an embodiment, contacting a tumorcell in vivo is accomplished by administering to a patient in need, forexample, by intravenous, subcutaneous, intraperitoneal, or intratumoralinjection, a therapeutically effective amount of a physiologicallytolerable composition comprising an anti-glycPD-L1 antibody as describedherein. The antibody may be administered parenterally by injection or bygradual infusion over time. Useful administration and delivery regimensinclude intravenous, intraperitoneal, oral, intramuscular, subcutaneous,intracavity, transdermal, dermal, peristaltic means, or direct injectioninto the tissue containing the tumor cells.

Therapeutic compositions comprising antibodies are conventionallyadministered intravenously, such as by injection of a unit dose, forexample. The term “unit dose” when used in reference to a therapeuticcomposition refers to physically discrete units suitable as unitarydosage for the subject, each unit containing a predetermined quantity ofactive material calculated to produce the desired therapeutic effect inassociation with the required diluent, i.e., carrier, or vehicle. Theanti-glycPD-L1 antibody containing compositions are administered in amanner compatible with the dosage formulation, and in a therapeuticallyeffective amount. The quantity to be administered depends on the subjectto be treated, capacity of the subject's system to utilize the activeingredient, and degree of therapeutic effect desired. Precise amounts ofactive ingredient required to be administered depend on the judgment ofthe practitioner and are peculiar to each individual. However, suitabledosage ranges for systemic application are disclosed herein and dependon the route of administration. Suitable regimens for initial andbooster administration are also contemplated and may typically involvean initial administration followed by repeated doses at one or moreintervals (hours) by a subsequent injection or other administration.Exemplary multiple administrations are suitable for maintainingcontinuously high serum and tissue levels of antibody. Alternatively,continuous intravenous infusion sufficient to maintain concentrations inthe blood in the ranges specified for in vivo therapies arecontemplated.

It is contemplated that an anti-glycPD-L1 antibody as described hereinmay be administered systemically or locally to treat disease, such as toinhibit tumor cell growth or to kill cancer cells in cancer patientswith locally advanced or metastatic cancers. The antibodies may beadministered alone or in combination with anti-proliferative drugs oranticancer drugs. In an embodiment, the anti-glycPD-L1 antibodies areadministered to reduce the cancer load in the patient prior to surgeryor other procedures. Alternatively, they can be administered at periodicintervals after surgery to ensure that any remaining cancer (e.g.,cancer that the surgery failed to eliminate) is reduced in size orgrowth capacity and/or does not survive. As noted hereinabove, atherapeutically effective amount of an antibody is a predeterminedamount calculated to achieve the desired effect. Thus, the dosage rangesfor the administration of an anti-glycPD-L1 antibody are those largeenough to produce the desired effect in which the symptoms of tumor celldivision and cell cycling are reduced. Optimally, the dosage should notbe so large as to cause adverse side effects, such as hyperviscositysyndromes, pulmonary edema, congestive heart failure, neurologicaleffects, and the like. Generally, the dosage will vary with age of,condition of, size and gender of, and extent of the disease in thepatient and can be determined by one of skill in the art such as amedical practitioner or clinician. Of course, the dosage may be adjustedby the individual physician in the event of any complication.

Treatment Methods

In certain embodiments, the compositions and methods as describedinvolve the administration of an anti-glycPD-L1 antibody as describedherein, alone, or in combination with a second or additional drug ortherapy. Such drug or therapy may be applied in the treatment of anydisease that is associated with PD-L1 or glycosylated PD-L1, preferablywith the interaction of human PD-L1 or glycosylated human PD-L1 withhuman PD-1. For example, the disease may be a cancer. The compositionsand methods comprising at least one anti-PD-L1 antibody thatpreferentially binds to glycosylated PD-L1 protein compared withunglycosylated PD-L1 or variant glycosylated PC-L1 have a therapeutic orprotective effect in the treatment of a cancer or other disease,particularly by preventing, reducing, blocking, or inhibiting thePD-1/PD-L1 interaction, thereby providing a therapeutic effect andtreatment.

The compositions and methods, including combination therapies, have atherapeutic or protective effect and may enhance the therapeutic orprotective effect, and/or increase the therapeutic effect of anotheranti-cancer or anti-hyperproliferative therapy. Therapeutic andprophylactic methods and compositions can be provided in a combinedamount effective to achieve the desired effect, such as the killing of acancer cell and/or the inhibition of cellular hyperproliferation. Thisprocess may involve administering an anti-glycPD-L1 antibody or abinding fragment thereof and a second therapy. The second therapy may ormay not have a direct cytotoxic effect. For example, the second therapymay be an agent that upregulates the immune system without having adirect cytotoxic effect. A tissue, tumor, and/or cell can be exposed toone or more compositions or pharmacological formulation(s) comprisingone or more of the agents (e.g., an antibody or an anti-cancer agent),or by exposing the tissue, tumor, and/or cell with two or more distinctcompositions or formulations, wherein one composition provides, forexample, 1) an antibody, 2) an anti-cancer agent, 3) both an antibodyand an anti-cancer agent, or 4) two or more antibodies. In someembodiments, the second therapy is also an anti-PD-L1 antibody,preferably an anti-glycPD-L1 antibody that preferentially bindsglycosylated PD-L1 versus unglycosylated PD-L1 or, in other embodiments,an anti-PD-1 antibody. Without limitation, exemplary anti-PD-1antibodies include pembrolizumab and nivolumab; exemplary anti-PD-L1antibodies include atezolizumab. Also, it is contemplated that such acombination therapy can be used in conjunction with chemotherapy,radiotherapy, surgical therapy, or immunotherapy.

By way of example, the terms “contacted” and “exposed,” when applied toa cell, are used herein to describe a process by which a therapeuticpolypeptide, preferably an anti-glycPD-L1 antibody as described herein,is delivered to a target cell or is placed in direct juxtaposition withthe target cell, particularly to bind specifically to the targetantigen, e.g., PD-L1, particularly, glycosylated PD-L1, expressed orhighly expressed on the surface of tumor or cancer cells. Such bindingby a therapeutic anti-glycPD-L1 antibody or binding fragment thereofprevents, blocks, inhibits, or reduces the interaction of the tumor orcancer cell-expressed PD-L1 with PD-1 on an effector T-cell, therebypreventing immunosuppression associated with the PD-L1/PD-1 interaction.In embodiments, a chemotherapeutic or radiotherapeutic agent are alsoadministered or delivered to the subject in conjunction with theanti-glycPD-L1 antibody or binding fragment thereof. To achieve cellkilling, for example, one or more agents are delivered to a cell in acombined amount effective to kill the cell or prevent it from dividing.

An anti-glycPD-L1 antibody may be administered before, during, after, orin various combinations relative to another anti-cancer treatment. Theadministrations may be in intervals ranging from concurrently to minutesto days to weeks before or after one another. In embodiments in whichthe antibody is provided to a patient separately from an anti-canceragent, it would be generally ensured that a significant period of timedid not expire between the time of each delivery, such that theadministered compounds would still be able to exert an advantageouslycombined effect for the patient. Illustratively, in such instances, itis contemplated that one may provide a patient with the antibody and theanti-cancer therapy within about 12 to 24 or 72 h of each other and,more particularly, within about 6-12 h of each other. In some situationsit may be desirable to extend the time period for treatmentsignificantly where several days (2, 3, 4, 5, 6, or 7) to several weeks(1, 2, 3, 4, 5, 6, 7, or 8) lapse between respective administrations.

In certain embodiments, a course of treatment or treatment cycle willlast 1-90 days or more (this range includes intervening days and thelast day). It is contemplated that one agent may be given on any day ofday 1 to day 90 (this such range includes intervening days and the lastday) or any combination thereof, and another agent is given on any dayof day 1 to day 90 (this such range includes intervening days and thelast day) or any combination thereof. Within a single day (24-hourperiod), the patient may be given one or multiple administrations of theagent(s). Moreover, after a course of treatment, it is contemplated thatthere may be a period of time at which no anti-cancer treatment isadministered. This time period may last, for example, for 1-7 days,and/or 1-5 weeks, and/or 1-12 months or more (this such range includesintervening days and the upper time point), depending on the conditionof the patient, such as prognosis, strength, health, etc. Treatmentcycles would be repeated as necessary. Various combinations oftreatments may be employed. In the representative examples ofcombination treatment regimens shown below, an antibody, such as ananti-glycPD-L1 antibody or binding fragment thereof is represented by“A” and an anti-cancer therapy is represented by “B”:

A/B/A B/A/B B/B/A A/A/B A/B/B B/A/A A/B/B/B B/A/B/B B/B/B/A B/B/A/BA/A/B/B A/B/A/B A/B/B/A B/B/A/A B/A/B/A B/A/A/B A/A/A/B B/A/A/A A/B/A/AA/A/B/A.

Administration of any antibody or therapy of the present embodiments toa patient will follow general protocols for the administration of suchcompounds, taking into account the toxicity, if any, of the agents.Therefore, in some embodiments there is a step of monitoring adverseevents and toxicity, particularly those that may be attributable tocombination therapy.

In an embodiment, a method is provided which involves the administrationof an anti-glycPD-L1 antibody alone or in combination with anotheranticancer agent to a patient in need thereof, i.e., a patient with acancer or tumor. Prior to administration of the anti-glycPD-L1 antibody,a sample of the patient's tumor or cancer may be evaluated for thepresence of PD-L1. If the results of such an evaluation reveals that thepatient's tumor or cancer is positive for glycosylated PD-L1, thepatient would be selected for treatment based on the likelihood thatpatient's glycPD-L1+ tumor or cancer would be more amenable to treatmentwith the anti-glycPD-L1 antibody and treatment may proceed with a morelikely beneficial outcome. A medical professional or physician mayadvise the patient to proceed with the anti-glycPD-L1 antibody treatmentmethod, and the patient may decide to proceed with treatment based onthe advice of the medical professional or physician. In addition, duringthe course of treatment, the patient's tumor or cancer cells may beassayed for the presence of glycosylated PD-L1 as a way to monitor theprogress or effectiveness of treatment. If the assay shows a change,loss, or decrease, for example, in glycosylated PD-L1 on the patient'stumor or cancer cells, a decision may be taken by the medicalprofessional in conjunction with the patient as to whether the treatmentshould continue or be altered in some fashion, e.g., a higher dosage,the addition of another anti-cancer agent or therapy, and the like.

Chemotherapy

A wide variety of chemotherapeutic agents may be used in accordance withthe treatment or therapeutic methods of the present embodiments. Theterm “chemotherapy” refers to the use of drugs to treat cancer. A“chemotherapeutic agent” connotes a compound or composition that isadministered in the treatment of cancer. Such agents or drugs arecategorized by their mode of activity within a cell, for example,whether and at what stage they affect the cell cycle and cell growth andproliferation. Alternatively, a chemotherapeutic agent may becharacterized based on its ability to directly cross-link DNA, tointercalate into DNA, or to induce chromosomal and mitotic aberrationsby affecting nucleic acid synthesis in a cell.

Nonlimiting examples of chemotherapeutic agents include alkylatingagents, such as thiotepa and cyclosphosphamide; alkyl sulfonates, suchas busulfan, improsulfan, and piposulfan; aziridines, such as benzodopa,carboquone, meturedopa, and uredopa; ethylenimines and methylamelamines,including altretamine, triethylenemelamine, trietylenephosphoramide,triethiylenethiophosphoramide, and trimethylolomelamine; acetogenins(especially bullatacin and bullatacinone); a camptothecin (including thesynthetic analogue topotecan); bryostatin; callystatin; CC-1065(including its adozelesin, carzelesin and bizelesin syntheticanalogues); cryptophycins (particularly cryptophycin 1 and cryptophycin8); dolastatin; duocarmycin (including the synthetic analogues, KW-2189and CB1-TM1); eleutherobin; pancratistatin; a sarcodictyin;spongistatin; nitrogen mustards, such as chlorambucil, chlornaphazine,cholophosphamide, estramustine, ifosfamide, mechlorethamine,mechlorethamine oxide hydrochloride, melphalan, novembichin,phenesterine, prednimustine, trofosfamide, and uracil mustard;nitrosureas, such as carmustine, chlorozotocin, fotemustine, lomustine,nimustine, and ranimnustine; antibiotics, such as the enediyneantibiotics (e.g., calicheamicin, especially calicheamicin gammalI andcalicheamicin omegaI1); dynemicin, including dynemicin A;bisphosphonates, such as clodronate; an esperamicin; as well asneocarzinostatin chromophore and related chromoprotein enediyneantibiotic chromophores, aclacinomysins, actinomycin, authrarnycin,azaserine, bleomycins, cactinomycin, carabicin, carminomycin,carzinophilin, chromomycinis, dactinomycin, daunorubicin, detorubicin,6-diazo-5-oxo-L-norleucine, doxorubicin (includingmorpholino-doxorubicin, cyanomorpholino-doxorubicin,2-pyrrolino-doxorubicin and deoxydoxorubicin), epirubicin, esorubicin,idarubicin, marcellomycin, mitomycins, such as mitomycin C, mycophenolicacid, nogalarnycin, olivomycins, peplomycin, potfiromycin, puromycin,quelamycin, rodorubicin, streptonigrin, streptozocin, tubercidin,ubenimex, zinostatin, and zorubicin; anti-metabolites, such asmethotrexate and 5-fluorouracil (5-FU); folic acid analogues, such asdenopterin, pteropterin, and trimetrexate; purine analogs, such asfludarabine, 6-mercaptopurine, thiamiprine, and thioguanine; pyrimidineanalogs, such as ancitabine, azacitidine, 6-azauridine, carmofur,cytarabine, dideoxyuridine, doxifluridine, enocitabine, and floxuridine;androgens, such as calusterone, dromostanolone propionate, epitiostanol,mepitiostane, and testolactone; anti-adrenals, such as mitotane andtrilostane; folic acid replenisher, such as frolinic acid; aceglatone;aldophosphamide glycoside; aminolevulinic acid; eniluracil; amsacrine;bestrabucil; bisantrene; edatraxate; defofamine; demecolcine;diaziquone; elformithine; elliptinium acetate; an epothilone; etoglucid;gallium nitrate; hydroxyurea; lentinan; lonidainine; maytansinoids, suchas maytansine and ansamitocins; mitoguazone; mitoxantrone; mopidanmol;nitraerine; pentostatin; phenamet; pirarubicin; losoxantrone;podophyllinic acid; 2-ethylhydrazide; procarbazine; PSKpolysaccharidecomplex; razoxane; rhizoxin; sizofiran; spirogermanium; tenuazonic acid;triaziquone; 2,2′,2″-trichlorotriethylamine; trichothecenes (especiallyT-2 toxin, verracurin A, roridin A and anguidine); urethan; vindesine;dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman;gacytosine; arabinoside (“Ara-C”); cyclophosphamide; taxoids, e.g.,paclitaxel and docetaxel gemcitabine; 6-thioguanine; mercaptopurine;platinum coordination complexes, such as cisplatin, oxaliplatin, andcarboplatin; vinblastine; platinum; etoposide (VP-16); ifosfamide;mitoxantrone; vincristine; vinorelbine; novantrone; teniposide;edatrexate; daunomycin; aminopterin; xeloda; ibandronate; irinotecan(e.g., CPT-11); topoisomerase inhibitor RFS 2000;difluorometlhylornithine (DMFO); retinoids, such as retinoic acid;capecitabine; carboplatin, procarbazine, plicomycin, gemcitabine,navelbine, farnesyl-protein tansferase inhibitors, transplatinum, andpharmaceutically acceptable salts, acids, or derivatives of any of theabove.

Radiotherapy

Radiotherapy includes treatments with agents that cause DNA damage.Radiotherapy has been used extensively in cancer and disease treatmentsand embraces what are commonly known as γ-rays, X-rays, and/or thedirected delivery of radioisotopes to tumor cells. Other forms of DNAdamaging factors are also contemplated, such as microwaves, proton beamirradiation (U.S. Pat. Nos. 5,760,395 and 4,870,287), andUV-irradiation. It is most likely that all of these factors affect abroad range of damage on DNA itself, on the precursors of DNA, on thereplication and repair of DNA, and on the assembly and maintenance ofchromosomes. Exemplary dosage ranges for X-rays range from daily dosesof 50 to 200 roentgens for prolonged periods of time (3 to 4 weeks) tosingle doses of 2000 to 6000 roentgens. Dosage ranges for radioisotopesvary widely and depend on the half-life of the isotope, the strength andtype of radiation emitted, the uptake by the neoplastic cells, andtolerance of the subject undergoing treatment.

Immunotherapy

In some embodiments of the methods, immunotherapies may be used incombination or in conjunction with administration of anti-glycPD-L1antibodies as described herein. In the context of cancer treatment,immunotherapeutics generally rely on the use of immune effector cellsand molecules to target and destroy cancer cells. Rituximab (RITUXAN®)is such an example. Other checkpoint inhibitors can also be administeredin combination, including ipilimumab. The anti-glycPD-L1 antibodies mayalso be administered in combination with other anti-PD-1 or anti-PD-L1inhibitors, such as antibodies against PD-L1, which includeatezolizumab, durvalumab, or avelumab, or antibodies against PD-1,including nivolumab, pembrolizumab, or pidilizumab. In addition, one ormore of the anti-glycPD-L1 antibodies of the embodiments may beadministered in combination with each other. The antibody alone mayserve as an effector of therapy or it may recruit other cells toactually affect cell killing. The antibody also may be conjugated to adrug or toxin (chemotherapeutic, radionuclide, ricin A chain, choleratoxin, pertussis toxin, etc.) and serve merely as a targeting agent.Alternatively, the effector may be a lymphocyte carrying a surfacemolecule that interacts, either directly or indirectly, with a tumorcell target, e.g., the PD-1 on T-cells/PD-L1 on tumor cells interaction.Various effector cells include cytotoxic T cells and natural killer (NK)cells.

In one aspect of immunotherapy, the tumor cell must bear some marker(protein/receptor) that is amenable to targeting. Optimally, the tumormarker protein/receptor is not present on the majority of other cells,such as non-cancer cells or normal cells. Many tumor markers exist andany of these may be suitable for targeting by another drug or therapyadministered with an anti-glycPD-L1 antibody in the context of thepresent embodiments. Common tumor markers include, for example, CD20,carcinoembryonic antigen (CEA), tyrosinase (p9′7), gp68, TAG-72, HMFG,Sialyl Lewis Antigen, MucA, MucB, PLAP, laminin receptor, erbB, andp155. An alternative aspect of immunotherapy is to combine anticancereffects with immune stimulatory effects. Immune stimulating moleculesalso exist and include cytokines, such as IL-2, IL-4, IL-12, GM-CSF,gamma-IFN; chemokines, such as MIP-1, MCP-1, IL-8; and growth factors,such as FLT3 ligand.

Examples of immunotherapies currently under investigation or in use areimmune adjuvants, e.g., Mycobacterium bovis, Plasmodium falciparum,dinitrochlorobenzene, and aromatic compounds (U.S. Pat. Nos. 5,801,005and 5,739,169; Hui et al., 1998, Infection Immun., 66(11):5329-5336;Christodoulides et al., 1998, Microbiology, 144(Pt 11):3027-3037);cytokine therapy, e.g., α, β, and γ interferons; IL-1, GM-CSF, and TNF(Bukowski et al., 1998, Clinical Cancer Res., 4(10):2337-2347; Davidsonet al., 1998, J. Immunother., 21(5):389-398; Hellstrand et al., 1998,Acta Oncologica, 37(4):347-353); gene therapy, e.g., TNF, IL-1, IL-2,and p53 (Qin et al., 1998, Proc. Natl. Acad. Sci. USA,95(24):14411-14416; Austin-Ward and Villaseca, 1998, Revista Medica deChile, 126(7):838-845; U.S. Pat. Nos. 5,830,880 and 5,846,945); andmonoclonal antibodies, e.g., anti-CD20, anti-ganglioside GM2, andanti-p185 (Hollander, 2012, Front. Immun., 3:3; Hanibuchi et al., 1998,Int. J. Cancer, 78(4):480-485; U.S. Pat. No. 5,824,311). It iscontemplated that one or more anti-cancer therapies may be employed withthe antibody therapies described herein.

Surgery

Approximately 60% of individuals with cancer undergo surgery of sometype, which includes preventative, diagnostic or staging, curative, andpalliative surgery. Curative surgery includes resection in which all orpart of cancerous tissue is physically removed, excised, and/ordestroyed and may be used in conjunction with other therapies, such asanti-glycPD-L1 antibody treatment as described herein, chemotherapy,radiotherapy, hormonal therapy, gene therapy, immunotherapy, and/oralternative therapies, as well as combinations thereof. Tumor resectionrefers to physical removal of at least part of a tumor. In addition totumor resection, treatment by surgery includes laser surgery,cryosurgery, electrosurgery, and microscopically-controlled surgery(Mohs' surgery). Upon excision of part or all of cancerous cells,tissue, or tumor, a cavity may be formed in the body. Treatment may beaccomplished by perfusion, direct injection, or local application of thearea with an additional anti-cancer therapy. Such treatment may berepeated, for example, every 1, 2, 3, 4, 5, 6, or 7 days, or every 1, 2,3, 4, and 5 weeks or every 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12months. These treatments may be of varying dosages as well.

Protein Purification

Protein, including antibody and, particularly, anti-glycPD-L1 antibody,purification techniques are well known to those of skill in the art.These techniques involve, at one level, the homogenization and crudefractionation of the cells, tissue, or organ into polypeptide andnon-polypeptide fractions. The protein or polypeptide of interest may befurther purified using chromatographic and electrophoretic techniques toachieve partial or complete purification (or purification tohomogeneity) unless otherwise specified. Analytical methods particularlysuited to the preparation of a pure protein or peptide are ion-exchangechromatography, size-exclusion chromatography, reverse phasechromatography, hydroxyapatite chromatography, polyacrylamide gelelectrophoresis, affinity chromatography, immunoaffinity chromatography,and isoelectric focusing. A particularly efficient method of purifyingpeptides is fast-performance liquid chromatography (FPLC) or evenhigh-performance liquid chromatography (HPLC). As is generally known inthe art, the order of conducting the various purification steps may bechanged, and/or certain steps may be omitted, and still result in asuitable method for the preparation of a substantially purifiedpolypeptide.

A purified polypeptide, such as an anti-glycPD-L1 antibody as describedherein, refers to a polypeptide which is isolatable or isolated fromother components and purified to any degree relative to itsnaturally-obtainable state. An isolated or purified polypeptide,therefore, also refers to a polypeptide free from the environment inwhich it may naturally occur, e.g., cells, tissues, organs, biologicalsamples, and the like. Generally, “purified” will refer to a polypeptidecomposition that has been subjected to fractionation to remove variousother components, and which composition substantially retains itsexpressed biological activity. A “substantially purified” compositionrefers to one in which the polypeptide forms the major component of thecomposition, and as such, constitutes about 50%, about 60%, about 70%,about 80%, about 90%, about 95%, or more of the protein component of thecomposition.

Various methods for quantifying the degree of purification ofpolypeptides, such as antibody proteins, are known to those of skill inthe art in light of the present disclosure. These include, for example,determining the specific activity of an active fraction, or assessingthe amount of polypeptides within a fraction by SDS/PAGE analysis. Apreferred method for assessing the purity of a fraction is to calculatethe specific activity of the fraction, to compare it to the specificactivity of the initial extract, and to thus calculate the degree ofpurity therein, assessed by a “fold purification number.” The actualunits used to represent the amount of activity will, of course, bedependent upon the particular assay technique chosen to follow thepurification, and whether or not the expressed polypeptide exhibits adetectable activity.

There is no general requirement that the polypeptide will always beprovided in its most purified state. Indeed, it is contemplated thatless substantially purified products may have utility in certainembodiments. Partial purification may be accomplished by using fewerpurification steps in combination, or by utilizing different forms ofthe same general purification scheme. For example, it is appreciatedthat a cation-exchange column chromatography performed utilizing an HPLCapparatus will generally result in a greater “fold” purification thanthe same technique utilizing a low pressure chromatography system.Methods exhibiting a lower degree of relative purification may haveadvantages in total recovery of protein product, or in maintaining theactivity of an expressed protein.

Affinity chromatography is a chromatographic procedure that relies onthe specific affinity between a substance (protein) to be isolated and amolecule to which it can specifically bind, e.g., a receptor-ligand typeof interaction. The column material (resin) is synthesized by covalentlycoupling one of the binding partners to an insoluble matrix. The columnmaterial is then able to specifically adsorb the substance from thesolution that is passed over the column resin. Elution occurs bychanging the conditions to those in which binding will be disrupted/willnot occur (e.g., altered pH, ionic strength, temperature, etc.). Thematrix should be a substance that does not adsorb molecules to anysignificant extent and that has a broad range of chemical, physical, andthermal stability. The ligand should be coupled in such a way as to notaffect its binding properties. The ligand should also provide relativelytight binding; however, elution of the bound substance should occurwithout destroying the sample protein desired or the ligand.

Size-exclusion chromatography (SEC) is a chromatographic method in whichmolecules in solution are separated based on their size, or in moretechnical terms, their hydrodynamic volume. It is usually applied tolarge molecules or macromolecular complexes, such as proteins andindustrial polymers. Typically, when an aqueous solution is used totransport the sample through the column, the technique is known as gelfiltration chromatography, versus the name gel permeationchromatography, which is used when an organic solvent is used as amobile phase. The underlying principle of SEC is that particles ofdifferent sizes will elute (filter) through a stationary phase atdifferent rates, resulting in the separation of a solution of particlesbased on size. Provided that all of the particles are loadedsimultaneously or near simultaneously, particles of the same size shouldelute together.

High-performance (aka high-pressure) liquid chromatography (HPLC) is aform of column chromatography used frequently in biochemistry andanalytical chemistry to separate, identify, and quantify compounds. HPLCutilizes a column that holds chromatographic packing material(stationary phase), a pump that moves the mobile phase(s) through thecolumn, and a detector that shows the retention times of the molecules.Retention time varies depending on the interactions between thestationary phase, the molecules being analyzed, and the solvent(s) used.

Pharmaceutical Preparations

Where clinical application of a pharmaceutical composition containing ananti-glycPD-L1 antibody or glycosylated PD-L1 polypeptide is undertaken,it is generally beneficial to prepare a pharmaceutical or therapeuticcomposition appropriate for the intended application. In general,pharmaceutical compositions may comprise an effective amount of one ormore polypeptides or additional agents dissolved or dispersed in apharmaceutically acceptable carrier. In certain embodiments,pharmaceutical compositions may comprise, for example, at least about0.1% of a polypeptide or antibody. In other embodiments, a polypeptideor antibody may comprise between about 2% to about 75% of the weight ofthe unit, or between about 25% to about 60%, for example, and any rangederivable there between, including the upper and lower values. Theamount of active compound(s) in each therapeutically useful compositionmay be prepared in such a way that a suitable dosage will be obtained inany given unit dose. Factors, such as solubility, bioavailability,biological half-life, route of administration, product shelf life, aswell as other pharmacological considerations, are contemplated by oneskilled in the art of preparing such pharmaceutical formulations, and assuch, a variety of dosages and treatment regimens may be desirable.

Further in accordance with certain aspects, the composition suitable foradministration may be provided in a pharmaceutically acceptable carrierwith or without an inert diluent. The carrier should be assimilable andinclude liquid, semi-solid, e.g., gels or pastes, or solid carriers.Examples of carriers or diluents include fats, oils, water, salinesolutions, lipids, liposomes, resins, binders, fillers, and the like, orcombinations thereof. As used herein, “pharmaceutically acceptablecarrier” includes any and all aqueous solvents (e.g., water,alcoholic/aqueous solutions, ethanol, saline solutions, parenteralvehicles, such as sodium chloride, Ringer's dextrose, etc.), non-aqueoussolvents (e.g., propylene glycol, polyethylene glycol, vegetable oil,and injectable organic esters, such as ethyloleate), dispersion media,coatings (e.g., lecithin), surfactants, antioxidants, preservatives(e.g., antibacterial or antifungal agents, anti-oxidants, chelatingagents, inert gases, parabens (e.g., methylparabens, propylparabens),chlorobutanol, phenol, sorbic acid, thimerosal), isotonic agents (e.g.,sugars, sodium chloride), absorption delaying agents (e.g., aluminummonostearate, gelatin), salts, drugs, drug stabilizers (e.g., buffers,amino acids, such as glycine and lysine, carbohydrates, such asdextrose, mannose, galactose, fructose, lactose, sucrose, maltose,sorbitol, mannitol, etc.), gels, binders, excipients, disintegrationagents, lubricants, sweetening agents, flavoring agents, dyes, fluid andnutrient replenishers, such like materials and combinations thereof, aswould be known to one of ordinary skill in the art. Except insofar asany conventional media, agent, diluent, or carrier is detrimental to therecipient or to the therapeutic effectiveness of the compositioncontained therein, its use in an administrable composition for thepractice of the methods is appropriate. The pH and exact concentrationof the various components in a pharmaceutical composition are adjustedaccording to well-known parameters. In accordance with certain aspects,the composition is combined with the carrier in any convenient andpractical manner, i.e., by solution, suspension, emulsification,admixture, encapsulation, absorption, grinding, and the like. Suchprocedures are routine for those skilled in the art.

In certain embodiments, the compositions may comprise different types ofcarriers depending on whether they are to be administered in solid,liquid, or aerosol form, and whether it needs to be sterile for theroute of administration, such as injection. The compositions can beformulated for administration intravenously, intradermally,transdermally, intrathecally, intra-arterially, intraperitoneally,intranasally, intravaginally, intrarectally, intramuscularly,subcutaneously, mucosally, orally, topically, locally, by inhalation(e.g., aerosol inhalation), by injection, by infusion, by continuousinfusion, by localized perfusion bathing target cells directly, via acatheter, via a lavage, in lipid compositions (e.g., liposomes), or byother methods or any combination of the forgoing as would be known toone of ordinary skill in the art. See, for example, Remington'sPharmaceutical Sciences, 18th Ed., 1990. Typically, such compositionscan be prepared as either liquid solutions or suspensions; solid orreconstitutable forms suitable for use to prepare solutions orsuspensions upon the addition of a liquid prior to injection can also beprepared; and, the preparations can also be emulsified.

The antibodies may be formulated into a composition in a free base,neutral, or salt form. Pharmaceutically acceptable salts include theacid addition salts, e.g., those formed with the free amino groups of aproteinaceous composition, or which are formed with inorganic acids,such as, for example, hydrochloric or phosphoric acids, or such organicacids as acetic, oxalic, tartaric, or mandelic acid. Salts formed withthe free carboxyl groups may also be derived from inorganic bases, suchas, for example, sodium, potassium, ammonium, calcium, or ferrichydroxides; or such organic bases as isopropylamine, trimethylamine,histidine, or procaine.

In further embodiments, a pharmaceutical lipid vehicle composition thatincludes polypeptides, one or more lipids, and an aqueous solvent may beused. As used herein, the term “lipid” refers to any of a broad range ofsubstances that are characteristically insoluble in water andextractable with an organic solvent. This broad class of compounds iswell known to those of skill in the art, and as the term “lipid” is usedherein, it is not limited to any particular structure. Examples includecompounds that contain long-chain aliphatic hydrocarbons and theirderivatives. A lipid may be naturally occurring or synthetic (i.e.,designed or produced by man). However, a lipid is usually a biologicalsubstance. Biological lipids are well known in the art, and include forexample, neutral fats, phospholipids, phosphoglycerides, steroids,terpenes, lysolipids, glycosphingolipids, glycolipids, sulphatides,lipids with ether- and ester-linked fatty acids, polymerizable lipids,and combinations thereof. Of course, compounds other than thosespecifically described herein that are understood by one of skill in theart as lipids are also encompassed by the compositions and methods. Oneof ordinary skill in the art would be familiar with the range oftechniques that can be employed for dispersing a composition in a lipidvehicle. For example, the antibody may be dispersed in a solutioncontaining a lipid, dissolved with a lipid, emulsified with a lipid,mixed with a lipid, combined with a lipid, covalently bonded to a lipid,contained as a suspension in a lipid, contained or complexed with amicelle or liposome, or otherwise associated with a lipid or lipidstructure by any means known to those of ordinary skill in the art. Thedispersion may or may not result in the formation of liposomes.

The term “unit dose” or “dosage” refers to physically discrete unitssuitable for use in a subject, each unit containing a predeterminedquantity of the therapeutic antibody or composition containing thetherapeutic antibody calculated to produce the desired responsesdiscussed above in association with its administration, i.e., theappropriate route and treatment regimen. The quantity to beadministered, both according to number of treatments and unit dose,depends on the effect desired. The actual dosage amount of a compositionof the present embodiments administered to a patient or subject can bedetermined by physical and physiological factors, such as body weight,the age, health, and sex of the subject, the type of disease beingtreated, the extent of disease penetration, previous or concurrenttherapeutic interventions, idiopathy of the patient, the route ofadministration, and the potency, stability, and toxicity of theparticular therapeutic substance. In other non-limiting examples, a dosemay also comprise from about 1 microgram/kg/body weight, about 5microgram/kg/body weight, about 10 microgram/kg/body weight, about 50microgram/kg/body weight, about 100 microgram/kg/body weight, about 200microgram/kg/body weight, about 350 microgram/kg/body weight, about 500microgram/kg/body weight, about 1 milligram/kg/body weight, about 5milligram/kg/body weight, about 10 milligram/kg/body weight, about 50milligram/kg/body weight, about 100 milligram/kg/body weight, about 200milligram/kg/body weight, about 350 milligram/kg/body weight, about 500milligram/kg/body weight, to about 1000 milligram/kg/body weight or moreper administration, and any range derivable therein. In non-limitingexamples of a derivable range from the numbers listed herein, a range ofabout 5 milligram/kg/body weight to about 100 milligram/kg/body weight,about 5 microgram/kg/body weight to about 500 milligram/kg/body weight,etc., can be administered, based on the numbers described above. Theforegoing doses include amounts between those indicated and are intendedto also include the lower and upper values of the ranges. Thepractitioner responsible for administration will, in any event,determine the concentration of active ingredient(s) in a composition andappropriate dose(s) for the individual subject.

The particular nature of the therapeutic composition or preparation isnot intended to be limiting. For example, suitable compositions may beprovided in formulations together with physiologically tolerable liquid,gel, or solid carriers, diluents, and excipients. In some embodiments,the therapeutic preparations may be administered to mammals forveterinary use, such as with domestic animals, and clinical use inhumans in a manner similar to other therapeutic agents. In general, thedosage required for therapeutic efficacy will vary according to the typeof use and mode of administration, as well as the particularizedrequirements of individual subjects, as described supra.

Glycosylated PD-L1 as a Biomarker

Provided are methods involving the use of at least one anti-glycPD-L1antibody as described in the embodiments. Such methods may be useful inbiomarker evaluations of the tumor or cancer cells obtained from asubject who has a cancer or tumor. Provided is a method to determinewhether a subject who has cancer also has a cancer or tumor thatexpresses glycosylated PD-L1 as a biomarker of PD-L1-bearing tumor orcancer cells, particularly, a detectable level of glycosylated PD-L1 onthe cell surface of such cells. For example, if the subject's cancer ortumor cells are tested and determined to express glycosylated PD-L1 onthe cell surface, then the subject is a candidate for treatment with ananti-glycPD-L1 antibody as described, alone, or in combination withanother anti-cancer agent, for example, would benefit from thetreatment. Such methods comprise obtaining a sample from a subjecthaving a cancer or tumor, testing the sample for the presence ofglycosylated PD-L1 on cells derived from the subject's cancer or tumorusing binding methods known and used in the art and as described herein,for example, using an anti-glycPD-L1 antibody of the embodiments, andadministering to the subject an effective amount of an anti-glycPD-L1antibody alone, or in combination with another anti-cancer agent, if thesubject's cancer or tumor is found to be positive for the cell surfaceexpression of glycosylated PD-L1 protein. Diagnosing the subject ashaving a cancer or tumor expressing glycosylated PD-L1 prior totreatment allows for more effective treatment and benefit to thesubject, as the administered anti-glycPD-L1 antibody is more likely toblock or inhibit the interaction of the subject's glycosylatedPD-L1-expressing cancer or tumor cells with the subject'sPD-1-expressing T-cells, thereby preventing immunosuppression of theT-cell activity and promoting killing of the tumor or cancer cells byactivated T-cell killing. In an embodiment, the method may involve firstselecting a subject whose cancer or tumor may be amenable to testing forthe presence of expressed glycosylated PD-L1 protein.

Similar methods may be used to monitor the presence of glycosylatedPD-L1 on a patient's tumor cells during a course of cancer treatment ortherapy, including combination treatments with an anti-glycPD-L1antibody and another anticancer drug or treatment, over time, as well asafter treatment has ceased. Such methods may also be used in companiondiagnostic methods in which an anti-cancer treatment regimen, orcombination treatment, involves testing or assaying a patient's tumor orcancer sample for glycosylated PD-L1-expressing tumor or cancer cells,prior to treatment and during the course of treatment, e.g., monitoring,to determine a successful outcome or the likelihood thereof.

Other Agents

It is contemplated that other agents may be used in combination withcertain aspects of the present embodiments to improve the therapeuticefficacy of treatment. These additional agents include agents thataffect the upregulation of cell surface receptors and GAP junctions,cytostatic and differentiation agents, inhibitors of cell adhesion,agents that increase the sensitivity of the hyperproliferative cells toapoptotic inducers, or other biological agents. Increases inintercellular signaling by elevating the number of GAP junctions mayincrease the anti-hyperproliferative effects on the neighboringhyperproliferative cell population. In other embodiments, cytostatic ordifferentiation agents may be used in combination with certain aspectsof the present embodiments to improve the anti-hyperproliferativeefficacy of the treatments. Inhibitors of cell adhesion are contemplatedto improve the efficacy of the present embodiments. Examples of celladhesion inhibitors are focal adhesion kinase (FAKs) inhibitors andLovastatin. It is further contemplated that other agents that increasethe sensitivity of a hyperproliferative cell to apoptosis, such as theantibody c225, could be used in combination with certain aspects of thepresent embodiments to improve the treatment efficacy.

Kits and Diagnostics

In another embodiment, a kit containing therapeutic agents and/or othertherapeutic and delivery agents is provided. In some embodiments, thekit is used for preparing and/or administering a therapy involving theanti-glycPD-L1 antibodies described herein. The kit may comprise one ormore sealed vials containing any of the pharmaceutical compositions asdescribed herein. The kit may include, for example, at least oneanti-glycosylated PD-L1 antibody, as well as reagents to prepare,formulate, and/or administer one or more anti-glycPD-L1 antibodies or toperform one or more steps of the described methods. In some embodiments,the kit may also comprise a suitable container means, which is acontainer that will not react with components of the kit, such as anEppendorf tube, an assay plate, a syringe, a bottle, or a tube. Thecontainer may be made from sterilizable materials, such as plastic orglass.

The kit may further include an instruction sheet that outlines theprocedural steps of the methods set forth herein, and will followsubstantially the same procedures as described herein or are known tothose of ordinary skill. The instruction information may be in acomputer readable medium containing machine-readable instructions that,when executed using a computer, cause the display of a real or virtualprocedure of delivering a pharmaceutically effective amount of thetherapeutic agent.

Fusions and Conjugates

The anti-glycosylated PD-L1 antibodies or glycosylated PD-L1polypeptides provided herein can also be expressed as fusion proteinswith other proteins or chemically conjugated to another moiety. In someembodiments, the antibodies or polypeptides have an Fc portion that canbe varied by isotype or subclass, can be a chimeric or hybrid, and/orcan be modified, for example to improve effector functions, controlhalf-life or tissue accessibility, augment biophysical characteristics,such as stability, and improve efficiency of production, which can beassociated with cost reductions. Many modifications useful in theconstruction of fusion proteins and methods for making them are known inthe art, for example, as reported by Mueller, J. P. et al., 1997, Mol.Immun. 34(6):441-452; Swann, P. G., 2008, Curr. Opin. Immunol.,20:493-499; and Presta, L. G., 2008, Curr. Opin. Immunol., 20:460-470.In some embodiments, the Fc region is the native IgG1, IgG2, or IgG4 Fcregion of the antibody. In some embodiments, the Fc region is a hybrid,for example a chimera containing IgG2/IgG4 Fc constant regions.Modifications to the Fc region include, but are not limited to, IgG4modified to prevent binding to Fc gamma receptors and complement; IgG1modified to improve binding to one or more Fc gamma receptors; IgG1modified to minimize effector function (amino acid changes); IgG1 withaltered/no glycan (typically by changing expression host); and IgG1 withaltered pH-dependent binding to FcRn. The Fc region can include theentire hinge region, or less than the entire hinge region of theantibody.

Another embodiment includes IgG2-4 hybrids and IgG4 mutants that havereduced binding to FcR which increase their half-life. RepresentativeIG2-4 hybrids and IgG4 mutants are described, for example, in Angal etal., 1993, Molec. Immunol., 30(1):105-108; Mueller et al., 1997, Mol.Immun., 34(6):441-452; and U.S. Pat. No. 6,982,323; all of which arehereby incorporated by references in their entireties. In someembodiments, the IgG1 and/or IgG2 domain is deleted. For example, Angalet al., Id., describe proteins in which IgG1 and IgG2 domains haveserine 241 replaced with a proline. In some embodiments, fusion proteinsor polypeptides having at least 10, at least 20, at least 30, at least40, at least 50, at least 60, at least 70, at least 80, at least 90 orat least 100 amino acids are contemplated.

In some embodiments, anti-glycosylated PD-L1 antibodies or glycosylatedPD-L1 polypeptides are linked to or covalently bind or form a complexwith at least one moiety. Such a moiety may be, but is not limited to,one that increases the efficacy of the antibody as a diagnostic or atherapeutic agent. In some embodiments, the moiety can be an imagingagent, a toxin, a therapeutic enzyme, an antibiotic, a radio-labelednucleotide, a chemotherapeutic agent, and the like.

In some embodiments, the moiety that is conjugated or fused to ananti-glycPD-L1 antibody or glycosylated polypeptide or portion thereofmay be an enzyme, a hormone, a cell surface receptor, a toxin (such as,without limitation, abrin, ricin A, pseudomonas exotoxin (i.e., PE-40),diphtheria toxin, ricin, gelonin, or pokeweed antiviral protein), aprotein (such as tumor necrosis factor, interferon (e.g., α-interferon,β-interferon), nerve growth factor (NGF), platelet derived growth factor(PDGF), tissue plasminogen activator (TPA), or an apoptotic agent (e.g.,tumor necrosis factor-a, tumor necrosis factor-β)), a biologicalresponse modifier (such as, for example, a lymphokine (e.g.,interleukin-1 (“IL-1”), interleukin-2 (“IL-2”), interleukin-6 (“IL-6”)),granulocyte macrophage colony stimulating factor (“GM-CSF”), granulocytecolony stimulating factor (“G-CSF”), or macrophage colony stimulatingfactor, (“M-CSF”)), or growth factors (e.g., growth hormone (“GH”))), acytotoxin (e.g., a cytostatic or cytocidal agent, such as paclitaxel,cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin,etoposide, tenoposide, vincristine, vinblastine, colchicine,doxorubicin, daunorubicin, dihydroxy anthracin dione, mitoxantrone,mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids,procaine, tetracaine, lidocaine, propranolol, monomethyl auristatin F(MMAF), monomethyl auristatin E (MMAE; e.g., vedotin) and puromycin andanalogs or homologs thereof), antimetabolites (e.g., methotrexate,6-mercaptopurine, 6-thioguanine, cytarabine, 5-fluorouracildecarbazine), alkylating agents (e.g., mechlorethamine, thioepachlorambucil, melphalan, BiCNU® (carmustine; BSNU) and lomustine (CCNU),cyclophosphamide, busulfan, dibromomannitol, streptozocin, mitomycin C,and cisdichlorodiamine platinum (II) (DDP) cisplatin), an anthracycline(e.g., daunorubicin (formerly daunomycin) and doxorubicin), anantibiotic (e.g., dactinomycin (formerly actinomycin), bleomycin,mithramycin, and anthramycin (AMC)), an anti-mitotic agent (e.g.,vincristine and vinblastine), or combinations thereof.

In a particular embodiment, the anti-glycPD-L1 antibodies may beconjugated to a biologically active drug or agent, such as a cytotoxicor chemotherapeutic agent, or a radionuclide, typically by chemicallinkers with labile bonds, to produce an anti-glycPD-L1 antibody-drugconjugate (ADC). Accordingly, when such ADCs are internalized into thecell, they act directly to kill the cell or target a molecule inside thecell, which leads to apoptosis or cell death. Such ADCs comprising theanti-glycPD-L1 antibodies described herein, particularly, monoclonal,humanized, chimeric, or human antibodies, combine the specific targetingof antibodies to glycosylated PD-L1 on tumor and cancer cells with thecancer-killing ability of cytotoxic drugs, thereby providing furtheradvantages for treatment and therapies with the anti-glycPD-L1antibodies. Techniques for preparing and using ADCs are known in the artand are not intended to be limiting for the anti-glycPD-L1 antibodiesdescribed herein. (See, e.g., Valliere Douglass, J. F., et al., 2015,Mol. Pharm., 12(6):1774-1783; Leal, M. et al., 2014, Ann. N.Y. Acad.Sci., 1321:41-54; Panowski, S. et al., 2014, mAbs, 6(1):34-45; Beck, A.2014, mAbs, 6(1):30-33; Behrens, C. R. et al., 2014, mAbs, 6(1):46-53;and Flygare, J. A. et al., 2013, Chem. Biol. Drug Des., 81(1):113-121).In embodiments, some or all of the above-described moieties,particularly, toxins and cytotoxins, may be conjugated to ananti-glycPD-L1 antibody to produce effective ADCs for treating cancer.

Techniques for conjugating therapeutic or cytotoxic moieties toantibodies are well known; See, e.g., Amon et al., “MonoclonalAntibodies For Immunotargeting Of Drugs In Cancer Therapy”, inMONOCLONAL ANTIBODIES AND CANCER THERAPY, Reisfeld et al. (eds.), 1985,pp. 243-56, Alan R. Liss, Inc.); Hellstrom et al., “Antibodies For DrugDelivery”, in CONTROLLED DRUG DELIVERY (2nd Ed.), Robinson et al.(eds.), 1987, pp. 623-53, Marcel Dekker, Inc.); Thorpe, “AntibodyCarriers Of Cytotoxic Agents In Cancer Therapy: A Review”, in MONOCLONALANTIBODIES '84: BIOLOGICAL AND CLINICAL APPLICATIONS, Pinchera et al.(eds.), 1985, pp. 475-506); “Analysis, Results, And Future ProspectiveOf The Therapeutic Use Of Radiolabeled Antibody In Cancer Therapy”, inMONOCLONAL ANTIBODIES FOR CANCER DETECTION AND THERAPY, Baldwin et al.(eds.), 1985, pp. 303-16, Academic Press; Thorpe et al., Immunol. Rev.62:119-158 (1982); Carter et al., Cancer J. 14(3):154-169 (2008); Alleyet al., Curr. Opin. Chem. Biol. 14(4):529-537 (2010); Carter et al.,Amer. Assoc. Cancer Res. Educ. Book. 2005(1):147-154 (2005); Carter etal., Cancer J. 14(3):154-169(2008); Chari, Acc. Chem Res. 41(1):98-107(2008); Doronina et al., Nat. Biotechnol. 21(7):778-784(2003); Ducry etal., Bioconjug Chem. 21(1):5-13(2010); Senter, Curr Opin. Chem. Biol.13(3):235-244 (2009); and Teicher, Curr Cancer Drug Targets.9(8):982-1004 (2009).

In some embodiments, antibodies and polypeptides as described herein maybe conjugated to a marker, such as a peptide, to facilitatepurification. In some embodiments, the marker is a hexa-histidinepeptide, i.e., the hemagglutinin “HA” tag, which corresponds to anepitope derived from the influenza hemagglutinin protein (Wilson, I. A.et al., Cell, 37:767-778 (1984)), or the “flag” tag (Knappik, A. et al.,Biotechniques 17(4):754-761 (1994)).

In other embodiments, the moiety conjugated to the antibodies andpolypeptides as described herein may be an imaging agent that can bedetected in an assay. Such imaging agents may be enzymes, prostheticgroups, radiolabels, nonradioactive paramagnetic metal ions, haptens,fluorescent labels, phosphorescent molecules, chemiluminescentmolecules, chromophores, luminescent molecules, bioluminescentmolecules, photoaffinity molecules, or colored particles or ligands,such as biotin. In embodiments, suitable enzymes include, but are notlimited to, horseradish peroxidase, alkaline phosphatase,beta-galactosidase, or acetylcholinesterase; prosthetic group complexesinclude, but are not limited to, streptavidin/biotin and avidin/biotin;fluorescent materials include, but are not limited to, umbelliferone,fluorescein, fluorescein isothiocyanate, rhodamine,dichlorotriazinylamine fluorescein, dansylchloride or phycoerythrin;luminescent materials include, but are not limited to, luminol;bioluminescent materials include, but are not limited to, luciferase,luciferin, and aequorin; radioactive materials include, but are notlimited to, bismuth (²¹³Bi), carbon (¹⁴C), chromium (⁵¹Cr), cobalt(⁵⁷Co), fluorine (¹⁸F), gadolinium (¹⁵³Gd, ¹⁵⁹Gd), gallium (⁶⁸Ga, ⁶⁷Ga),germanium (⁶⁸Ge), holmium (¹⁶⁶Ho), indium (¹¹⁵In, ¹¹³In, ¹¹²In, ¹¹¹In),iodine (¹³¹I, ¹²⁵I, ¹²³I, ¹²¹I), lanthanium (¹⁴⁰La), lutetium (¹⁷⁷Lu),manganese (⁵⁴Mn), molybdenum (⁹⁹Mo), palladium (¹⁰³Pd), phosphorous(³²P), praseodymium (¹⁴²Pr), promethium (¹⁴⁹Pm), rhenium (¹⁸⁶Re, ¹⁸⁸Re),rhodium (¹⁰⁵Rh), ruthemium (⁹⁷Ru), samarium (¹⁵³Sm), scandium (⁴⁷Sc),selenium (⁷⁵Se), strontium (⁸⁵Sr), sulfur (³⁵S), technetium (⁹⁹Tc),thallium (²⁰¹Ti), tin (¹¹³Sn, ¹¹⁷Sn), tritium (³H), xenon (¹³³Xe),ytterbium (¹⁶⁹Yb ¹⁷⁵Yb) yttrium (⁹⁰Y), zinc (⁶⁵Zn); positron emittingmetals using various positron emission tomographies, and nonradioactiveparamagnetic metal ions.

The imaging agent may be conjugated to the antibodies or polypeptidesdescribed herein either directly or indirectly through an intermediate(such as, for example, a linker known in the art) using techniques knownin the art. See, for example, U.S. Pat. No. 4,741,900 which reports onmetal ions that can be conjugated to antibodies and other molecules asdescribed herein for use as diagnostics. Some conjugation methodsinvolve the use of a metal chelate complex employing, for example, anorganic chelating agent, such as diethylenetriaminepentaacetic acidanhydride (DTPA); ethylenetriaminetetraacetic acid;N-chloro-p-toluenesulfonamide; and/ortetrachloro-3-6α-diphenylglycouril-3, attached to the antibody.Monoclonal antibodies can also be reacted with an enzyme in the presenceof a coupling agent such as glutaraldehyde or periodate. Conjugates withfluorescein markers can be prepared in the presence of these couplingagents or by reaction with an isothiocyanate.

In some embodiments, the anti-glycPD-L1 antibodies or glycPD-L1polypeptides as described herein may be conjugated to a second antibodyto form an antibody heteroconjugate, for example, as described in U.S.Pat. No. 4,676,980. Such heteroconjugate antibodies can additionallybind to haptens (e.g., fluorescein), or to cellular markers (e.g.,without limitation, 4-1-BB, B7-H4, CD4, CD8, CD14, CD25, CD27, CD40,CD68, CD163, CTLA4, GITR, LAG-3, OX40, TIM3, TIM4, TLR2, LIGHT, ICOS,B7-H3, B7-H7, B7-H7CR, CD70, CD47) or to cytokines (e.g., IL-7, IL-15,IL-12, IL-4 TGF-beta, IL-10, IL-17, IFNγ, Flt3, BLys) or chemokines(e.g., CCL21).

In some embodiments, the anti-glycosylated PD-L1 antibodies orglycosylated PD-1 polypeptides described herein can also be attached tosolid supports, which can be useful for carrying out immunoassays orpurification of the target antigen or of other molecules that arecapable of binding to the target antigen that has been immobilized tothe support via binding to an antibody or antigen binding fragment asdescribed herein. Such solid supports include, but are not limited to,glass, cellulose, polyacrylamide, nylon, polystyrene, polyvinyl chlorideor polypropylene.

EXAMPLES

The following examples are included to demonstrate embodiments thatrelate to the anti-glycPD-L1 antibodies that preferentially bindglycosylated PD-L1 compared with unglycosylated PD-L1 and/or PD-L1glycosylation mutants, and methods of use described herein.Representative anti-glycPD-L1 antibodies are exemplified. It should beappreciated by those of skill in the art that the disclosedanti-glycPD-L1 antibodies are examples and are not intended to belimiting.

Example 1 Materials and Methods

Cell Culture, Stable Transfectants, and Transfection.

All cells were obtained from American Type Culture Collection (ATCC).These cells were grown in in DMEM/F12 or RPMI 1640 medium supplementedwith 10% fetal bovine serum (FBS). PD-L1 stable transfectants inMDA-MB-468, BT549 and 293T cells were selected using puromycin(InvivoGen, San Diego, Calif., USA). For transient transfection, cellswere transiently transfected with DNA, such as DNA encoding PD-L1, usingSN liposomes (Hu, M. C. et al., 2004, Cell, 117:225-237) andLipofectamine™ 2000 (Life Technologies, Carlsbad, Calif., USA).

Generation of Stable Cells Using Lentiviral Infection.

The lentiviral-based shRNA (pGIPZ plasmids) used to knockdown expressionof PD-L1 (Shen, J. et al., 2013, Nature, 497:383-387) in cells waspurchased from the shRNA/ORF Core Facility (UT MD Anderson CancerCenter). Based on knock-down efficiency of PD-L1 protein expression inMDA-MB-231 or A431 cells, the inventors selected two shPD-L1 clones forthis study. The mature antisense sequences are as follows:TCAATTGTCATATTGCTAC (shPD-L1 #1, SEQ ID NO: 34), TTGACTCCATCTTTCTTCA(shPD-L1 #5, SEQ ID NO: 35). Using a pGIPZ-shPD-L1/Flag-PD-L1 dualexpression construct to knock down endogenous PD-L1 and reconstituteFlag-PD-L1 simultaneously, the inventors established endogenous PD-L1knock-down and Flag-PD-L1 WT or 4NQ mutant expressing cell lines. Togenerate lentivirus-expressing shRNA for PD-L1 and Flag-PD-L1, theinventors transfected 293T cells with pGIPZ-non-silence (for vectorcontrol virus), pGIPZ-shPD-L1, or pGIPZ-shPD-L1/PD-L1 WT, orpGIPZ-shPD-L1/PD-L1 4NQ mutant with FuGENE 6 transfection reagent.Twenty-four hours after transfection the medium was changed, and thenthe medium was collected at 24-hour intervals. The collected mediumcontaining lentivirus was centrifuged to eliminate cell debris, andfiltered through 0.45-μm filters. Cells were seeded at 50% confluence 12hours before infection, and the medium was replaced with mediumcontaining lentivirus. After infection for 24 hours, the medium wasreplaced with fresh medium and the infected cells were selected with 1μg/ml puromycin (InvivoGen).

Plasmids.

A human PD-L1 clone was obtained from the shRNA/ORF Core Facility (UT MDAnderson Cancer Center, Houston, Tex., USA) and cloned into pCDHlentiviral expression vectors to establish PD-L1-Flag or PD-L1-Mycexpression cell lines using known molecular biological techniques. Inaddition, human PD-L1 nucleic acid was also cloned into pEGFP-N1 andpCMV-HA mammalian cell expression vectors for transient transfection.pCDH/PD-L1-Flag expression vector was used as a template to generate thePD-L1-Flag NQ mutants N35Q, N192Q, N200Q, N219Q, and 4NQ(N35Q/N192Q/N200Q/N219Q) by performing site directed mutagenesis usingprimers presented in Table 4 below. To create a pGIPZ-shPD-L1/Flag-PD-L1dual expression construct to knock down endogenous PD-L1 andreconstitute Flag-PD-L1 simultaneously, a shPD-L1 construct (shPD-L1 #5)which targets the 3»-UTR region of PD-L1 mRNA was selected. TheFlag-PD-L1 wild type (WT) or 4NQ mutant DNA was cloned intopGIPZ-shPD-L1 (Thermo Scientific, Pittsburgh, Pa., USA) which expressesshRNA specific for endogenous PD-L1. All constructs were confirmed usingenzyme digestion and DNA sequencing.

TABLE 4 Primers for site directed mutagenesis Primers Sequences (5′to 3′) N35Q Forward (SEQ ID NO: 36)gtggtagagtatggtagccaaatgacaattgaatgcaaa Reverse (SEQ ID NO: 37)tttgcattcaattgtcatttggctaccatactctaccac N192Q Forward (SEQ ID NO: 38)gagaggagaagcttttccaggtgaccagcacactgag Reverse (SEQ ID NO: 39)ctcagtgtgctggtcacctggaaaagcttctcctctc N200Q Forward (SEQ ID NO: 40)gaccagcacactgagaatccagacaacaactaatgagat Reverse (SEQ ID NO: 41)atctcattagttgttgtctggattctcagtgtgctggtc N219Q Forward (SEQ ID NO: 42)gagagaggagaagcttttccaagtgaccagcacactgaga Reverse (SEQ ID NO: 43)tctcagtgtgctggtcacttggaaaagcttctcctctctc

qRT-PCR assays were performed to measure the expression of mRNA (Shen etal., 2013, Nature, 497:383-7; and Chang et al., 2011, Nature cellbiology, 13:317-23 (see Table 5 below). Cells were washed twice with PBSand immediately lysed in QIAzol. The lysed sample was subjected to totalRNA extraction using RNeasy Mini Kit (Qiagen, Hilden, Germany). Tomeasure the expression of mRNA, cDNA was synthesized from 1 μg purifiedtotal RNA by SuperScript III First-Strand cDNA synthesis system usingrandom hexamers (Life Technologies) according to the manufacturer'sinstructions. qPCR was performed using a real-time PCR machine (iQ5,BioRad, Hercules, Calif., USA). All the data analysis was performedusing the comparative Ct method. Results were first normalized tointernal control β-actin mRNA.

TABLE 5 Primers for qRT-PCR. Gene Sequences (5′ to 3′) B4GALT2Forward (SEQ ID NO: 44) gcataacgaacctaaccctcag Reverse (SEQ ID NO: 45)gcccaatgtccactgtgata B4GALT3 Forward (SEQ ID NO: 46) gtaacctcagtcacctgccReverse (SEQ ID NO: 47) attccgctccacaatctctg B3GNT3Forward (SEQ ID NO: 48) tcttcaacctcacgctcaag Reverse (SEQ ID NO: 49)gtgtgcaaagacgtcatcatc B3GAT1 Forward (SEQ ID NO: 50)caccatcaccctcctttctattc Reverse (SEQ ID NO: 51) gaacaacaggtctgggatttctB3GAT2 Forward (SEQ ID NO: 52) gccttttgccatcgacatgReverse (SEQ ID NO: 53) agtcagattcttgcatccctg ST6GAL1Forward (SEQ ID NO: 54) caaggagagcattaggaccaag Reverse (SEQ ID NO: 55)ccccattaaacctcaggactg ST3GAL4 Forward (SEQ ID NO: 56)tcgtcatggtgtggtattcc Reverse (SEQ ID NO: 57) caggaagatgggctgatcc MAN2A2Forward (SEQ ID NO: 58) gaccgcactcatcttacacc Reverse (SEQ ID NO: 59)ggaggttggctgaaggaatac MAN2B1 Forward (SEQ ID NO: 60) tcccctgctttaaccatcgReverse (SEQ ID NO: 61) ttgtcacctatactggcgttg UGGT1Forward (SEQ ID NO: 62) ctgagtgatggaacgagtgag Reverse (SEQ ID NO: 63)tagagatgaccagatgcaacg MGAT3 Forward (SEQ ID NO: 64)gagtccaacttcacggcttat Reverse (SEQ ID NO: 65) agtggtccaggaagacatagaMGAT5 Forward (SEQ ID NO: 66) tgtgagggaaagatcaagtggReverse (SEQ ID NO: 67) gctctccaaggtaaatgaggac MOGSForward (SEQ ID NO: 68) ccactgagttcgtcaagagg Reverse (SEQ ID NO: 69)acttccttgccatctgtcac GNPTAB Forward (SEQ ID NO: 70) tggctcgctgataagttctgReverse (SEQ ID NO: 71) gtgagtctggtttgggagaag ACTBForward (SEQ ID NO: 72) gcaaagacctgtacgccaaca Reverse (SEQ ID NO: 73)tgcatcctgteggcaatg

Antibodies and Chemicals.

The following antibodies were used in the experiments described in theExamples: Flag (F3165; Sigma-Aldrich, St. Louis, Mo., USA); Myc(11667203001; Roche Diagnostics, Indianapolis, Ind., USA); HA(11666606001; Roche Diagnostics); PD-L1 (13684; Cell SignalingTechnology, Danvers, Mass., USA); PD-L1 (329702; BioLegend, San Diego,Calif., USA,); PD-L1 (GTX117446; GeneTex, Irvine, Calif., USA); PD-L1(AF156; R&D Systems, Minneapolis, Minn., USA); PD-1 (ab52587; Abcam,Cambridge, Mass., USA); α-Tubulin (B-5-1-2; Sigma-Aldrich); and β-Actin(A2228; Sigma-Aldrich).

Immunoblot Analysis, Immunocytochemistry and Immunoprecipitation.

Immunoblot analysis was performed as described previously (Lim et al.,2008, Gastroenterology, 135:2128-2140; and Lee et al., 2007, Cell,130:440-455). Image acquisition and quantification of band intensitywere performed using an Odyssey® infrared imaging system (LI-CORBiosciences, Lincoln, Nebr., USA). For immunoprecipitation, the cellswere lysed in buffer (50 mM Tris-HCl, pH 8.0, 150 mM NaCl, 5 mMethylenediaminetetraacetic acid (EDTA) and 0.5% Nonidet P-40 (NP-40))and centrifuged at 16,000×g for 30 minutes to remove debris. Clearedlysates were subjected to immunoprecipitation with antibodies. Forimmunocytochemistry, cells were fixed in 4% paraformaldehyde at roomtemperature for 15 minutes, permeabilized in 5% Triton X-100 for 5minutes, and then were stained using primary antibodies. The secondaryantibodies used were anti-mouse Alexa Fluor 488 or 594 dye conjugateand/or anti-rabbit Alexa Fluor 488 or 594 dye conjugate (LifeTechnologies). Nuclei were stained with 4′,6-diamidino-2-phenylindole(DAPI blue) (Life Technologies). After mounting, the cells werevisualized using a multiphoton confocal laser-scanning microscope (CarlZeiss, Thornwood, N.Y., USA).

PD-L1 and PD-1 (PD-L1/DP-1) Interaction Assay.

To measure the interaction of PD-1 protein and PD-L1 protein, cells werefixed in 4% paraformaldehyde at room temperature for 15 minutes and thenwere incubated with recombinant human PD-1 Fc chimera protein (R&DSystems) for 1 hour. The secondary antibodies used were anti-human AlexaFluor 488 dye conjugate (Life Technologies). Nuclei were stained with4′,6-diamidino-2-phenylindole (DAPI blue) (Life Technologies). Thefluorescence intensity of Alexa Fluor 488 dye was then measured using amicroplate reader Synergy Neo (BioTeK, Winooski, Vt., USA) andnormalized to the intensity by total protein quantity. To take an image,after mounting, the cells were visualized using a confocallaser-scanning microscope (Carl Zeiss).

Glycosylation Analysis of PD-L1.

To confirm glycosylation of PD-L1 protein, cell lysates were treatedwith the enzymes PNGase F, Endo H, O-glycosidase (New England BioLabs,Ipswich, Mass., USA) as described by the manufacturer. To stainglycosylated PD-L1 protein, purified PD-L1 protein was stained using theGlycoprotein Staining Kit (Peirce/Thermo Scientific) as described by themanufacturer.

Identification of N-Glycopeptide.

Purified His tagged PD-L1 protein was reduced with 10 mM dithiothreitol(DTT) at 37° C. for 1 hour, alkylated with 50 mM iodoacetamide in 25 mMammonium bicarbonate buffer for 1 hour in the dark at room temperature,and then treated overnight with sequencing grade trypsin at anenzyme-to-substrate ratio of 1:50 at 37° C. The digested products werethen diluted with formic acid to a final concentration with 0.1%, andfurther cleaned up by ZipTip C18 (Millipore) before LC-MS/MS analysis.LC-MS/MS data were acquired at the Academia Sinica Mass SpectrometryFacility at IBC. The peptide mixture was analyzed by nanospray LC-MS/MSon an Orbitrap Fusion Tribrid (Thermo Scientific) coupled to an UltiMate3000 RSLCnano System (Dionex) with trap column Acclaim PepMap 100 (2cm×100 μm i.d) (Dionex). Peptide mixtures were loaded onto a AcclaimPepMap RSLC 25 cm×75 μm i.d. column (Dionex) and separated at a flowrate of 500 nL/min using a gradient of 5% to 35% solvent B (100%acetonitrile with 0.1% formic acid) for 60 minutes. Solvent A was 0.1%formic acid in water. The parameters used for MS and MS/MS dataacquisition under the HCD parallel with CID mode were: top speed modewith 3 s cycle time; FTMS: scan range (m/z)=400-2000; resolution=120 K;AGC target=2×10⁵; maximum injection time (ms)=50; FTMSn (HCD): isolationmode=quadrupole; isolation window=1.6; collision energy (%)=30 withstepped collision energy 5%; resolution=30 K; AGC target=5×10⁴; maximuminjection time (ms)=60; ITMSn (CID): isolation mode=quadrupole;isolation window=1.6; collision energy (%)=30; AGC target=1×10⁴. Rawdata were converted to Mascot generic format (MGF) by ProteomeDiscoverer 1.4. For glycopeptide identification, the HCD MS² data weresearched using Byonic (version 2.0-25) with the following searchparameters: peptide tolerance=2 ppm; fragment tolerance=6 ppm; missedcleavages=1; modifications: carbamidomethyl cysteine (fixed), methionineoxidation (common 2), deamidation at N (rare 1). The glycopeptide hitssuggested by Byonic were further checked manually by combining HCD andCID MS² results.

Statistical Analysis.

Data in bar graphs represents mean fold change relative to untreated orcontrol groups with standard deviation of three independent experiments.Statistical analyses were performed using SPSS (Ver. 20, SPSS, Chicago,Ill.). The correlation between protein expression and BLBC subset wasanalyzed using Spearman's correlation and Mann-Whitney test. Student's ttest was performed for experimental data. A P value <0.05 was consideredstatistically significant.

Example 2 PD-L1 Protein Expression Analysis

To unravel and elucidate the underlying mechanism of PD-L1, the proteinexpression of PD-L1 was examined in human tumor tissues and cancer celllines. FIGS. 1A and 1B and FIGS. 2A-2D illustrate protein expression inlung, breast, colon and ovarian cancer cell lines by Western blotanalysis; FIG. 3A shows binding of PD-L1 protein in cells by differentPD-L1 antibodies. It was observed that a majority of PD-L1 protein wasdetected at ˜45 kDa (black circle), but a smaller fraction also appearedat 33 kDa (black arrowhead). Knocking down PD-L1 by lentiviralshort-hairpin RNA (shRNA) targeting either the coding sequence(shPD-L1#1) or the 3′UTR (shPD-L1#5) downregulated expression of boththe 33- and 45-kDa forms of PD-L1 (FIG. 3B). Reconstitution of PD-L1restored expression of both forms in the shPD-L1#5 clone (FIG. 1C; FIG.3C shows the vector design). These results showed that both bands on theWestern blot are PD-L1 protein and that the higher molecular weight formof PD-L1 is indicative of posttranslational modifications.

Glycosylated proteins frequently produce heterogeneous patterns in theWestern blot, as observed for the higher molecular weight (˜45 kDa) ofPD-L1. To test whether the glycosylation pattern observed for PD-L1corresponded to the glycosylated form, MDA-MB 231 and HeLa cells weretreated with recombinant glycosidase (Peptide-N-Glycosidase F; PNGase F)to remove N-glycan structure and then were subjected to Western blotanalysis. As shown in FIG. 3D, a significant portion of the 45-kDa PD-L1was reduced to the 33-kDa form of PD-L1 upon PNGase F treatment.Consistently, positive staining of the glycan structure was observed inpurified His-tagged PD-L1, but not in the presence of PNGase F (FIG.1D). These results demonstrate that the higher molecular weight of PD-L1is indeed the glycosylated form of the PD-L1 protein.

To recapitulate the expression of PD-L1 protein in cells, variousoverexpression constructs were generated to mimic endogenous expressionof the protein. To avoid possible cleavage at the N-terminal signalingpeptide, different tag sequences were fused at either the N- or theC-terminus (FIGS. 4A and 4B, above the blot). Similar to the resultsfrom endogenous PD-L1 expression analysis, transient transfection of allGFP-, HA-, Flag- or Myc-tagged PD-L1 had a ˜15 kDa molecular-weightshift from its actual size on the Western blot (FIGS. 1E and 4A and 4B).In contrast to PNGase F treatment, which removes the all of the N-glycanstructure on the PD-L1 protein, the addition of recombinant glycosidase,endoglycosidase H (Endo H), only partially reduced PD-L1 glycosylation,suggesting that complex types of N-linked glycan structures (containingboth high mannose and hybrid types) exist predominantly on PD-L1(Stanley, P., 2011, Cold Spring Harbor perspectives in biology, 3).Furthermore, glycosylation of PD-L1 was completely inhibited when cellswere treated with the N-linked glycosylation inhibitor, Tunicamycin™,(FIGS. 1F and 4A-4D), but not O-glycosidase (FIG. 4E). Together, theseresults indicate that PD-L1 is extensively N-linked glycosylated in thecells tested (Heifetz, A., et al., 1979, Biochemistry, 18:2186-2192).

Example 3 Glycosylation Analyses

Western blot analysis using two PD-L1-specific antibodies (anti-PD-L1and anti-hB7-H1) indicated that PD-L1 glycosylation occurred on itsextracellular domain (ECD, recognized by anti-hB7-H1) but not on itsintracellular domain (ICD, recognized by anti-PD-L1) (FIGS. 1F and 4C).To pinpoint the glycosylation sites, a sequence alignment of the PD-L1amino acid sequences from different species was performed to search forevolutionarily conserved NXT motifs, a consensus N-glycosylationrecognition sequence (Schwarz, F. et al., 2011, Current opinion instructural biology, 21, 576-582). Consistent with the earlier prediction(Cheng et al., 2013, The Journal of biological chemistry, 288:11771-85;and Vigdorovich et al., 2013, Structure, 21:707-17, four NXT motifs wereidentified (FIG. 1G and FIGS. 5A and 5B). To confirm if these sequenceswere indeed glycosylated, the tryptic peptides of a purified human PD-L1were analyzed by nano LC-MS/MS. Glycopeptides carrying complex typeN-glycans were identified for each of the 4 N-glycosylation sites (FIGS.6A-61I), consistent with the apparent resistance to Endo H treatment(FIG. 1E). A series of asparagine (N) to glutamine (Q) substitutionswere generated to determine the specific glycosylation site(s) on thePD-L1 protein. All four mutants, N35Q, N192Q, N200Q, and N219Q,exhibited a certain degree of reduction in glycosylation compared withthe WT PD-L1 (FIG. 1H, lanes 2, 3, 4, and 5). No detectable differencesin glycosylation were observed for the three non-NXT NQ PD-L1 mutants(FIG. 1H, lanes 11, 12, and 13). In addition, PD-L1 glycosylation wascompletely ablated in the PD-L1 4NQ variants in which all fourasparagines were mutated to glutamine as indicated by the absence ofsignals corresponding to the glycosylated form at 45 kDa (FIG. 111, lane10 (4NQ) and lane 14 (WT)). Based on the crystal structure of thePD-1/PD-L1 complex (Lin, D. Y. et al., 2008, Proceedings of the NationalAcademy of Sciences of the United States of America, 105, 3011-3016),these four glycosylation sites of PD-L1 (N35, N192, N200 and N219) areexposed on the surface of the protein. Mutation of the PD-L1glycosylation sites (PD-L1 4NQ) did not affect the overall structurebased on the prediction. These results suggest that PD-L1 existsexclusively as an N-glycosylated glycoprotein in the cells and that allfour NXT motifs are glycosylated.

Example 4 Functionality of the PD-L1 Glycophenotype

PD-L1 WT and 4NQ mutants were stably expressed in endogenousPD-L1-depleted MDA-MB-468 and BT549 cells. Using these cell lines, PD-1and PD-L1 binding affinity were analyzed. As shown, the associationbetween glycosylation variant PD-L1 4NQ and PD-1 was decreased (FIG.7A). In vitro binding experiments further demonstrated thatglycosylation is required for the PD-L1 and PD-1 association (FIG. 7B).T cell-mediated tumor cell killing was measured in vitro by co-culturingBT549 PD-L1 WT and PD-L1 4NQ expressing stable cell lines with humanprimary T cells (time-lapse microscopy). Consistent with the loss ofPD-1 binding, the PD-L1 4NQ stable cell line showed more T cell-mediatedkilling of cancer cells (FIG. 7C). In addition, the immunosuppressivefunction of PD-L1 was measured in vivo in a syngeneic 4T1 mouse model inwhich tumor growth was measured in BALB/c mice that had received eitherPD-L1 WT or PD-L1 4NQ expressing 4T1 cells. Compared with mice havingcells that expressed PD-L1 WT, the mice having cells that expressedPD-L1 4NQ showed reduced tumor size and more activated cytotoxic T cells(FIGS. 7D and 7E). Together, these data demonstrate that the loss ofPD-L1 glycosylation impairs its interaction with PD-1 and impairs theability of the PD-1/PD-L1 interaction to allow tumor cells to evadeimmune surveillance by T-cells. Accordingly, tumor cells in which PD-L1is non glycosylated, or is aberrantly glycosylated, provide targets thatare amenable to be killed by functional effector T-cells. This mechanismof preventing or blocking tumor cells from escaping T-cell immunesurveillance by impaired glycosylation of their membrane-expressed PD-L1further corroborates that the integrity of the PD-L1 glycophenotype isrequired for its immunosuppressive function.

Example 5 Production and Screening of Glycosylated PD-L1-BindingMonoclonal Antibodies

Hybridomas producing monoclonal antibodies generated againstglycosylated human PD-L1 were obtained by the fusion of SP2/0 murinemyeloma cells with spleen cells isolated from human PD-L1-immunizedBALB/c mice (n=6) (Antibody Solution, Inc.) according to standardizedprotocol. Before fusion, sera from the immunized mice were validated forbinding to the PD-L1 immunogen using FACS analysis. Monoclonal antibody(MAb)-producing hybridomas were generated. The isotype of all of theMAbs was IgG1. The hybridomas that produced antibodies were again testedfor specificity.

To identify anti-glycPD-L1 MAbs that were specific for and whichpreferentially bound glycosylated PD-L1 antigen (i.e., glycosylatedPD-L1 specific MAbs) versus non-glycosylated PD-L1, different types ofassays were performed. In a screening assay to detect preferentialbinding of MAbs to glycosylated PD-L1, antibody binding was determinedbased on the measurement of fluorescence intensity through FACS analysis(using cell membrane bound proteins). By way of example, the assay wasperformed using the BT549 human breast cancer cell line. Illustratively,BT549 cells overexpressing PD-L1 WT (fully glycosylated) were labeledwith biotin according to conventional procedures and then mixed withBT549 cells overexpressing PD-L1 4NQ (fully unglycosylated PD-L1variant). The mixed cells were incubated with anti-PD-L1 antibodies,e.g., anti-glycPD-L1 antibodies, and were further incubated withsecondary antibodies conjugated with FITC as detection agent. Afterwashing, fluorescence intensity (measured fluorescence intensity, MFI)was measured via FACS/flow cytometry analysis to assess the relativebinding of the anti-PC-L1 antibodies to membrane bound PD-L1 WT (oncells) or to 4NQ PD-L1 (on cells). Antibodies that exhibitedsignificantly higher MFI on WT PD-L1 versus 4NQ PD-L1 were selected forfurther evaluation. Results for the fluorescence binding analysis of theSTM004 and STM115 MAbs are presented in Table 6 below, which shows theMFI values for antibody binding to BT549 cells expressing wild type(glycosylated) PD-L1, (BT549PD-L1WT Cells) versus antibody binding toBT549 cells expressing variant (non-glycosylated 4NQ) PD-L1, (BT549PD-L14NQ Cells). The experimental results in Table 6 show an approximately5-fold higher MFI value for STM004 MAb binding to BT549PD-L1WT cells(glycosylated PD-L1-expressing cells) compared with BT549PD-L1 4NQ cells(non-glycosylated PD-L1-expressing cells). An over 2-fold higher MFIvalue was determined for STM115 binding to BT549PD-L1WT cells comparedwith BT549PD-L1 4NQ cells.

TABLE 6 Measured Fluorescence Intensity Values for Anti-glycPD-L1 MAbsMFI (BT549PD- MFI (BT549PD- MAb L1WT Cells) L1 4NQ Cells) STM004 42.538.70 STM115 51.14 21.31Based on the binding analysis, forty-two candidate MAb-producinghybridomas were selected, grown in ADCF medium, and their supernatantcontaining monoclonal antibody was concentrated and purified.

In some cases, the purified MAbs were further tested for their abilityto neutralize or inhibit the interaction between PD-L1 and PD-1(PD-L1/PD-1 interaction) using a live-cell imaging assay, Incucyte™,(Essen Bioscience). For this assay, BT-549 cells expressing PD-L1 wereincubated with anti-human PD-L1 antibody and with fluorescent-labeledPD-1-Fc fusion proteins. Ligand and receptor binding was quantified byIncycyte™ Zoom every hour, according to the manufacturer's instructions.Based on this assay, it was found that of the 42 MAbs tested, 15 MAbscompletely blocked the binding of PD-L1 to PD-1. Some of the 15 MAbsthat showed strong blocking efficacy also bound non-glycosylated PD-L1to some extent.

In another assay, both glycosylated human PD-L1 protein andnon-glycosylated PD-L1, i.e., PD-L1 protein treated with PNGase F, werecoated onto a solid phase and tested for binding affinity of the MAbs tothe PD-L1 antigens. It will be understood that “PD-L1 antigen” issynonymous with “PD-L1 protein.” Twelve (12) of the MAbs showed a higheraffinity interaction with glycosylated PD-L1 protein compared tonon-glycosylated PD-L1 protein (PNGase F treated protein). For furtherspecificity analysis, selected MAbs were analyzed by Western Blot andFACS flow cytometry analysis. From the various analyses, MAbs, such asSTM004 and STM115, were found to specifically bind the glycosylated formof PD-L1 compared with the non-glycosylated form of PD-L1, which furthervalidated the specificity of these MAbs for glycosylated PD-L1 antigen.

Example 6 Identification of Binding Regions of Specific GlycosylatedPD-L1-Binding Antibodies

To identify the regions of monoclonal anti-glycPD-L1 antibodies whichbound to glycosylated PD-L1, wild type (glycosylated) PD-L1 (PD-L1 WT),and the glycosylation variant proteins N35/3NQ, N192/3NQ, N200/3NQ, andN219/3NQ (in which one of the glycosylation sites at position 35, 192,200 or 219 is the wild type asparagine (N) at that position and theother three positions have been mutated to glutamine (Q) have beenmutated so it is not glycosylated) (FIG. 8A) were overexpressed in PD-L1knockdown BT549 cells. As determined by Western blot, some MAbsrecognized particular PD-L1 mutants with higher levels of bindingcompared with other PD-L1 mutants, demonstrating that such MAbs weresite-specific. For example, MAb STM004 recognized and bound the N35/3NQmutant, but did not bind the N192/3NQ, N200/3NQ, or N219/3Q mutants,demonstrating that this antibody bound to the N35 region of PD-L1 (FIG.8B). Further, Western blot analysis using liver cancer cell lysate alsorevealed a differential pattern of PD-L1 glycosylation for arepresentative anti-glycPD-L1 antibody such as STM004 (FIG. 8C).

The histopathologic relevance of these MAbs was further demonstrated byimmunohistochemical (IHC) staining. In a cytospin staining analysis, theanti-glycPD-L1 monoclonal antibodies consistently recognized and boundthe glycosylated portion of the PD-L1 protein, but not unglycosylatedPD-L1 protein. In a human triple negative breast cancer patient sample,the anti-glycPD-L1 monoclonal antibodies also showed membrane andcytoplasm staining in a 1:30 ratio. These data demonstrated that theanti-glycPD-L1 monoclonal antibodies can be used in biomarker analysesfor detection of glycosylated PD-L1 as biomarker.

Example 7 Epitope Mapping of Glycosylated PD-L1-Binding Antibodies

Epitope mapping for the mouse monoclonal anti-glycPD-L1 antibody STM004was performed by CovalX AG (Switzerland). To determine the nature of theepitope, e.g., either linear or conformational, recognized by theanti-glycPD-L1 antibodies generally, and the STM004 MAb in particular,studies were conducted to evaluate whether the interaction between PD-L1protein as target antigen and the anti-glycPD-L1 antibodies could beinhibited by unstructured peptides generated by proteolysis of the PD-L1antigen. If the peptides generated by complete proteolysis of the PD-L1antigen are able to inhibit the binding of the antigen by the antibody,the interaction is not based on conformation, and the epitope is linear.A simple competition assay with a bank of overlapping peptides generatedfrom the sequence of the antigen is sufficient to determine the sequenceof the epitope. Alternatively, if the peptides generated by completeproteolysis of the PD-L1 antigen are unable to inhibit the binding ofthe antigen by the antibody, the conformation of the target isdetermined to be necessary for interaction, and the epitope isconformational, e.g., continuous (with a special conformation such as aloop) or discontinuous (due to tertiary structure). To further elucidatebinding to a conformational epitope, covalent labeling, peptide mapping,and high resolution mass spectrometry were also employed.

Competition assays showed that peptides generated from the PD-L1 antigendid not inhibit the binding of anti-glycPD-L1 monoclonal antibodies asdescribed herein, such as representative MAb STM004, to the PD-L1antigen, confirming that the epitopic regions of PD-L1 that wererecognized by these antibodies and the representative STM004 MAb areconformational and not linear. Using chemical cross-linking, High-MassMALDI mass spectrometry and nLC-Orbitrap mass spectrometry, theinteraction surfaces between the PD-L1 protein and the antibodies werecharacterized. Competition assays using pepsin proteolysis of PD-L1,mixture of the resulting pepsin-generated PD-L1 peptides with antibodiesand intact PD-L1 protein, and analysis of the antigen/antibodyinteraction by known methods showed no detectable inhibition of bindingof the STM004 monoclonal antibody to the PD-L1 antigen by the PD-L1peptides. Accordingly, the epitope on PD-L1 recognized by the anti-PD-L1MAb STM004 was determined to be conformational and not linear.

STM004 was determined to bind to an epitope on PD-L1 in which itcontacts the amino acid residues at positions Y56, K62 and K75 (asnumbered in SEQ ID NO: 1) within residues 48 to 78 of SEQ ID NO: 1.

STM115 was determined to bind to an epitope on PD-L1 in which itcontacts the amino acid residues at positions K62, H69 and K75 (asnumbered in SEQ ID NO: 1) within residues 61 to 78 of SEQ ID NO: 1.

Example 8 T Cell Killing Assay

T cell killing assays were utilized to determine the cytotoxic activityof anti-glycPD-L1 monoclonal antibodies as described herein on tumorcells. The protocol followed is as follows: On Day 0, serum-containingmedium was removed from glycosylated wild type PD-L1-(PD-L1 WT)expressing BT549 RFP target cell cultures and gently rinsed twice withPBS. Cells were harvested and counted. The cell suspension wascentrifuged (1000 RPM, 4 minutes) and the cell pellet was resuspended inculture medium at 50,000 cells/mL. Using a manual multichannel pipette,the cells were seeded (100 μL/well, i.e., 5000 cells/well) into everywell of a flat-bottom microplate. The plate was allowed to stand atambient temperature for 30 minutes and then was positioned into aIncuCyte ZOOM® live-cell imager where it was left to equilibrate for 20minutes before scheduling the first scan. Twenty-four hour (24 hr)repeat scanning (10× objective) was scheduled for every 3 hours, withthe first scan commencing immediately. Cell confluence was monitored forthe next 18 hours (overnight) until the desired confluence (e.g., 20%)was achieved.

The next morning, the day of the assay (i.e., Day 1), a 10 μM solutionof IncuCyte™ Caspase 3/7 apoptosis green fluorescence detection reagent(Essen BioScience 4440) was prepared in assay medium (4× final assayconcentration of 2.5 μM) and warmed to 37° C. in an incubator. Ananti-CD3 antibody (100 ng/mL)+IL-2 (10 ng/mL) T cell activator treatmentwas prepared at 4× final assay concentration in assay medium and warmedto 37° C. Test MAbs were also prepared. The target cell plate wasremoved from the incubator and the medium was aspirated, taking care notto damage the cell layer. Using a multichannel pipette, 25 μL of thewarmed caspase 3/7 solution was transferred into each well. Thereafter,25 μL of the warmed anti-CD3 antibody+IL-2, and the antibodies, wereplaced into the appropriate wells of the cell plate. An additional 50 μLmedium containing the effector cells (PBMCs or Total T cells) was addedto form a total assay volume of 100 μL. The de-bubbled cell plate waspositioned in the IncuCyte ZOOM® instrument and allowed to equilibratefor 20 minutes prior to the first scan. 24-hr repeat scanning wasscheduled for every 2 to 3 hours for up to 5 days. (Objective 10×;Vessel Type: Corning 3596; Scan Mode: Standard; Scan Pattern: 2 imagesper well; Channel: Phase+“Green” (+“Red” if NucLight™ Red target cellswere used).

For analysis, target-cell apoptosis was quantified in the IncuCyte™software by counting the total number of “large” green-fluorescentobjects (nuclei) in the field of view over time. The proliferation oftarget cells was measured from the red object count, corresponding tothe number of red cell nuclei. Data were expressed as the number offluorescent objects per mm². Data showed that addition of antibodies asdescribed herein, specifically STM004, enhanced tumor cell killing (FIG.9).

Example 9 Binding Assay

To determine whether an anti-glycPD-L1 monoclonal antibody as describedherein specifically inhibits the interaction of PD-1 and PD-L1, thefollowing binding assay was performed. On Day 0 of the assay,serum-containing medium was removed from PD-L1-expressing BT549 targetcell culture and gently rinsed twice with D-PBS. Cells were harvestedand counted. The cell suspension was centrifuged (1000 RPM, 5 minutes)and the cell pellet was resuspended in culture medium at 50,000cells/mL. A manual multichannel pipette was used to seed the cells (100μL/well, i.e., 5000 cells/well) into every well of a flat-bottommicroplate. The plate was allowed to stand at ambient temperature for 30minutes. Thereafter, the plates containing the cells were incubatedovernight in a 5% CO₂ incubator.

On Day 1 of the assay (i.e., the next morning), culture mediumcontaining 1 μg/mL PD-1/Fc and a 1:400 dilution of Alex Fluor 488-goatanti-human IgG was prepared and warmed to 37° C. in an incubator. Thecell plate was removed from the incubator and the medium was aspirated,taking care not to damage the cell layer. 50 μL of test antibody wasadded to each well in a dose-dependent manner. 50 μL of the culturemedium containing PD-1/Fc and Alex Fluor 488-goat anti-human IgG wasadded to every well. The cell plate was positioned in the IncuCyte ZOOM®instrument and allowed to equilibrate for 20 minutes prior to the firstscan. 24-hr automated repeat scanning (10×) was scheduled for every 1-2hours for up to 24 hours. Objective: 10×; Vessel Type: Corning 3596;Scan Mode: Standard; Scan Pattern: 4 images per well; Channel:Phase+“Green”.

FIG. 10A shows that representative MAb STM004 inhibited binding ofPD-1/Fc to cells expressing PD-L1 in a dose dependent manner. Theresults of control assays are shown in FIG. 10B.

All of the methods disclosed and claimed herein can be made and executedwithout undue experimentation in light of the present disclosure. Whilethe compositions and methods have been described in terms of embodimentsand preferred embodiments, it will be apparent to those of skill in theart that variations may be applied to the methods and in the steps or inthe sequence of steps of the methods described herein without departingfrom the concept, spirit and scope of that which is described. Morespecifically, it will be apparent that certain agents which are bothchemically and physiologically related may be substituted for the agentsdescribed herein while the same or similar results would be achieved.All such similar substitutes and modifications apparent to those skilledin the art are deemed to be within the spirit, scope and concept of thedescribed embodiments as defined by the appended claims.

All patents, published patent applications, and other publications citedherein are hereby incorporated by reference in the present application.

What is claimed is:
 1. An isolated antibody which selectively binds toglycosylated PD-L1 relative to unglycosylated PD-L1 and inhibits bindingof glycosylated PD-L1 to PD-1.
 2. The isolated antibody of claim 1 whichis recombinantly engineered, chimeric, humanized or fully human.
 3. Theisolated antibody of claim 1 or 2, wherein the antibody selectivelybinds to amino acid residues within regions of the PD-L1 proteincomprising amino acid positions 35, 192, 200 and/or 219 in SEQ ID NO: 1relative to unglycosylated PD-L1.
 4. The isolated antibody of any one ofclaims 1 to 3, wherein the antibody binds to glycosylated PD-L1 with aK_(d) that is less than half of the K_(d) exhibited by the antibodybinding to unglycosylated PD-L1.
 5. The isolated antibody of claim 4,wherein the antibody binds to glycosylated PD-L1 with a K_(d) at least10 times less than the K_(d) exhibited by the antibody binding tounglycosylated PD-L1.
 6. The isolated antibody of any one of claims 1 to5, wherein the antibody binds glycosylated PD-L1 with an affinity offrom 5-20 nM.
 7. The isolated antibody of any one of claims 1 to 3,wherein the antibody, which is directly or indirectly detectable by afluorescent label, preferentially binds to cells expressing glycosylatedPD-L1 with a measured fluorescence intensity (MFI) that is 2-fold to10-fold higher than the MFI exhibited by the antibody binding to cellsexpressing unglycosylated PD-L1 in a cell flow cytometry assay.
 8. Theisolated antibody of claim 7, wherein the antibody preferentially bindsto cells expressing glycosylated PD-L1 with a MFI that is 3-fold to5-fold or more higher than the MFI exhibited by the antibody binding tocells expressing unglycosylated PD-L1.
 9. The isolated antibody of anyone of claims 1 to 8, which specifically binds to an epitope ofglycosylated PD-L1 comprising at least one of amino acids 56, 62, 69 and75 of SEQ ID NO:
 1. 10. The isolated antibody of claim 9, wherein theepitope comprises amino acids within region L48 to H78 of SEQ ID NO: 1.11. The isolated antibody of claim 9, wherein the epitope comprisesamino acids within regions D61 to H78 of SEQ ID NO:
 1. 12. The isolatedantibody of any one of claims 1 to
 8. which specifically binds to theepitope of PD-L1 recognized by the monoclonal antibody (MAb) STM004 orMAb STM115.
 13. The isolated antibody of any one of claims 1 to 8 whichcompetes or cross competes for specific binding to glycosylated PD-L1with MAb STM004 or MAb STM115.
 14. The isolated antibody of any one ofclaims 1 to 8, which comprises the heavy chain variable (V_(H)) domainor the light chain variable (V_(L)) domain of MAb STM004 or MAb STM115.15. The isolated antibody of any one of claims 1 to 8, which comprisesheavy chain CDRs1-3 and/or light chain CDRs1-3 from MAb STM004 or MAbSTM115.
 16. The isolated antibody of any one of claims 1 to 8, whereinthe V_(H) domain has an amino acid sequence of SEQ ID NO: 3 or SEQ IDNO:
 19. 17. The isolated antibody of any one of claim 1 to 8 or 16,wherein the V_(L) domain has an amino acid sequence of SEQ ID NO: 11 orSEQ ID NO:
 27. 18. The isolated antibody of any one of claims 1 to 8,wherein the V_(H) domain has an amino acid sequence of SEQ ID NO: 3 andthe V_(L) has an amino acid sequence of SEQ ID NO:
 11. 19. The isolatedantibody of any one of claims 1 to 8, wherein the V_(H) domain has anamino acid sequence of SEQ ID NO: 19 and the V_(L) domain has an aminoacid sequence of SEQ ID NO:
 27. 20. The isolated antibody of any one ofclaim 1 to 8 or 17, wherein the V_(H) domain has an amino acid sequencethat is at least 90% identical to the amino acid sequence of SEQ ID NO:3 or SEQ ID NO:
 19. 21. The isolated antibody of any one of claim 1 to8, 16, or 20, wherein the V_(L) domain has an amino acid sequence thatis at least 90% identical to the amino acid sequence of SEQ ID NO: 11 orSEQ ID NO:
 27. 22. The isolated antibody of any one of claim 14 or 16 to21, which comprises a human constant domain.
 23. The isolated antibodyof any one of claims 1 to 8, which has a V_(H) domain comprising a CDRH1 with an amino acid sequence of SEQ ID NO: 4, a CDR H2 with an aminoacid sequence of SEQ ID NO: 6, and a CDR H3 with an amino acid sequenceof SEQ ID NO: 8, or a V_(H) domain comprising a CDR H1 with an aminoacid sequence of SEQ ID NO: 5, a CDR H2 with an amino acid sequence ofSEQ ID NO: 7, and a CDR H3 with an amino acid sequence of SEQ ID NO: 9.24. The isolated antibody of any one of claim 1 to 8 or 23, which has aV_(L) domain comprising a CDR L1 with an amino acid sequence of SEQ IDNO: 12, a CDR L2 with an amino acid sequence of SEQ ID NO: 14, and a CDRL3 with an amino acid sequence of SEQ ID NO:
 16. 25. The isolatedantibody of any one of claims 1 to 8, which has a V_(H) domaincomprising a CDR H1 with an amino acid sequence of SEQ ID NO: 20, a CDRH2 with an amino acid sequence of SEQ ID NO: 22, and a CDR H3 with anamino acid sequence of SEQ ID NO: 24, or a V_(H) comprising a CDR H1with an amino acid sequence of SEQ ID NO: 21 a CDR H2 with an amino acidsequence of SEQ ID NO: 23, and a CDR H3 with an amino acid sequence ofSEQ ID NO:
 25. 26. The isolated antibody of any one of claim 1 to 8 or25, which has a V_(L) domain comprising a CDR L1 with an amino acidsequence of SEQ ID NO: 28, a CDR L2 with an amino acid sequence of SEQID NO: 30, and a CDR L3 with an amino acid sequence of SEQ ID NO: 32.27. The isolated antibody of any one of claim 1 to 8 or 24, which has aV_(H) domain comprising CDRs H1, H2 and H3 with amino acid sequencesthat have 1, 2, 3, 4, or 5 amino acid substitutions in 1, 2 or 3 CDRshaving the amino acid sequences of SEQ ID NO: 4, SEQ ID NO: 6, and SEQID NO: 8, respectively, or having the amino acid sequences of SEQ ID NO:5, SEQ ID NO: 7, and SEQ ID NO: 9, respectively.
 28. The isolatedantibody of any one of claim 1 to 8, 23 or 26, which has a V_(L) domaincomprising CDRs L1, L2 and L3 with amino acid sequences that have 1, 2,3, 4, or 5 amino acid substitutions in 1, 2 or 3 CDRs having the aminoacid sequences of SEQ ID NO: 12, SEQ ID NO: 14, and SEQ ID NO: 16,respectively.
 29. The isolated antibody of any one of claim 1 to 8 or26, which has a V_(H) domain comprising CDRs H1, H2 and H3 with aminoacid sequences that have 1, 2, 3, 4, or 5 amino acid substitutions in 1,2 or 3 CDRs having the amino acid sequences of SEQ ID NO: 20, SEQ ID NO:22, and SEQ ID NO: 24, respectively, or SEQ ID NO: 21, SEQ ID NO: 23,and SEQ ID NO: 25, respectively.
 30. The isolated antibody of any one ofclaim 1 to 8, 25, or 29, which has a V_(L) domain comprising CDRs L1, L2and L3 with amino acid sequences that have 1, 2, 3, 4, or 5 amino acidsubstitutions in 1, 2 or 3 CDRs having the amino acid sequences of SEQID NO: 28, SEQ ID NO: 30, and SEQ ID NO: 32, respectively.
 31. Theisolated antibody of any one of claim 15, or 23 to 30, which has humanframework regions.
 32. The isolated antibody of any one of claim 15, or23 to 30, which has heavy or light chain human framework regions having1, 2, 3, 4, 5, or 6 amino acid substitutions.
 33. The antibody accordingto any one of claims 1-32, wherein the antibody is an IgG, IgM, IgAantibody, or an antigen binding fragment thereof.
 34. The antibodyaccording to any one of claims 1-32, wherein the antibody is a Fab′, aF(ab′)2, a F(ab′)3, a monovalent scFv, a bivalent scFv, or a singledomain antibody.
 35. The antibody according to any one of claims 1-34,wherein the antibody is conjugated to an imaging agent, achemotherapeutic agent, a toxin or a radionuclide.
 36. An isolatednucleic acid molecule comprising a nucleotide sequence of SEQ ID NOs: 2or
 18. 37. An isolated nucleic acid molecule comprising a nucleotidesequence of SEQ ID NO: 10 or
 26. 38. An isolated nucleic acid moleculecomprising a nucleotide sequence encoding a V_(H) domain and/or a V_(L)domain of an antibody of any one of claims 1 to
 35. 39. A compositioncomprising the antibody of any one of claims 1-35 in a pharmaceuticallyacceptable carrier, diluent, excipient, or vehicle.
 40. A method oftreating a PD-L1 positive cancer in a subject in need, said methodcomprising administering to the subject having cancer an effectiveamount of the antibody according to any one of claims 1-35.
 41. Themethod of claim 40, wherein the subject is a human.
 42. The method ofclaim 40 or claim 41, wherein the cancer is a breast cancer, lungcancer, head & neck cancer, prostate cancer, esophageal cancer, trachealcancer, skin cancer brain cancer, liver cancer, bladder cancer, stomachcancer, pancreatic cancer, ovarian cancer, uterine cancer, cervicalcancer, testicular cancer, colon cancer, rectal cancer or skin cancer.43. The method of any one of claims 40 to 42, wherein the cancer is ahematological cancer.
 44. The method of any one of claims 40 to 43,wherein the antibody is administered in a pharmaceutically acceptablecomposition.
 45. The method of claim 44, wherein the antibody isadministered systemically, intravenously, intradermally, intratumorally,intramuscularly, intraperitoneally, subcutaneously or locally.
 46. Themethod of any one of claims 38 to 45, further comprising administeringat least a second anticancer drug and/or anticancer therapy to thesubject.
 47. The method of claim 46, wherein the second anticancertherapy is a surgical therapy, chemotherapy, radiation therapy,cryotherapy, hormonal therapy, immunotherapy or cytokine therapy.
 48. Amethod of assaying for the presence of glycosylated PD-L1 in abiological sample, said method comprising contacting a biological samplewith an antibody according to any one of claims 1 to 35, whereindetection of binding of said antibody indicates that the samplecomprises glycosylated PD-L1.
 49. The method of claim 48, wherein thesample is cell sample.
 50. The method of claim 49, wherein the cellsample is from a cancer or tumor of a subject.
 51. An isolatedpolypeptide comprising a fragment of at least 7 contiguous amino acidsof human PD-L1 comprising at least one amino acid corresponding toposition N35, N192, N200, or N219 of SEQ ID NO: 1, wherein at least oneof the amino acids corresponding to position N35, N192, N200 or N219 ofPD-L1 is glycosylated.
 52. The isolated polypeptide of claim 51, whereinthe polypeptide comprises at least 8-20 contiguous amino acids of humanPD-L1.
 53. The isolated polypeptide of claim 51 or claim 52, wherein thepolypeptide comprises a glycosylated amino acid corresponding toposition N35, N192, N200, and/or N219 of SEQ ID NO:
 1. 54. Thepolypeptide of any one of claims 51 to 53, wherein the polypeptide isfused or conjugated at its amino or carboxy terminus to an immunogenicpolypeptide.
 55. A composition comprising the polypeptide of any one ofclaims 51 to 54 in a pharmaceutically acceptable carrier, excipient,diluent, or vehicle.
 56. The composition of claim 55, which is animmunogenic composition.
 57. The immunogenic composition according toclaim 56, further comprising an adjuvant.
 58. An isolated nucleic acidmolecule comprising a nucleotide sequence encoding a V_(H) domain of theantibody of claim 1, wherein the nucleotide sequence is at least 90-98%identical to the nucleotide sequence of SEQ ID NOs: 2 or 18 and/or anucleotide sequence encoding a V_(L) domain of the antibody of claim 1,wherein the nucleotide sequence is at least 90-98% identical to thenucleotide sequence of SEQ ID NOs: 19 or
 26. 59. The isolated nucleicacid molecule of claim 58, wherein the nucleotide sequence encoding theV_(H) domain is 95-99% identical to SEQ ID NOs: 2 or 18 and/or thenucleotide sequence encoding the V_(L) domain is 95 to 99% identical toSEQ ID NOs: 10 or
 26. 60. A method of identifying a candidate cancerpatient for treatment with an agent that blocks binding of PD-L1 withPD-1, the method comprising testing for the presence of glycosylatedPD-L1 on cells derived from a sample of the patient's cancer cells usingan antibody of any one of claims 1 to 35, wherein if said cells arepositive for glycosylated PD-L1, said patient is a candidate for saidtreatment.
 61. The method of claim 60, which further comprisesadministering to a patient identified as a candidate cancer patient aneffective amount of an agent that prevents binding of glycosylated PD-L1to PD-1.
 62. The method of claim 61, wherein the agent that preventsbinding of glycosylated PD-L1 to PD-1 is an isolated antibody of any oneof claims 1 to
 34. 63. The method of claim 62, wherein the isolatedantibody is administered in combination with another anti-cancer drug ortherapeutic.